Most often in January, 30 days.
Highest follower count seen that year: 11,891.
January
Jan 1 08:00–16:00 UTC Jan 2 07:00–10:00, 15:00–18:00 UTC Jan 4 10:00–12:00, 20:00–22:00 UTC Jan 5 00:00–01:00, 04:00–06:00, 08:00–09:00, 16:00–18:00 UTC Jan 6 06:00–07:00, 09:00–12:00 UTC Jan 7 03:00–04:00, 09:00–12:00, 19:00–21:00 UTC Jan 8 10:00–12:00, 18:00–20:00 UTC Jan 9 02:00–04:00, 07:00–08:00, 10:00–12:00 UTC Jan 10 06:00–09:00, 15:00–19:00 UTC Jan 11 08:00–11:00, 21:00–22:00 UTC Jan 12 03:00–06:00, 09:00–11:00, 16:00–19:00 UTC Jan 13 00:00–03:00, 18:00–19:00 UTC Jan 14 06:00–12:00 UTC Jan 15 03:00–04:00, 11:00–15:00, 17:00–20:00 UTC Jan 16 05:00–06:00, 08:00–09:00 UTC Jan 17 09:00–10:00, 16:00–17:00 UTC Jan 18 07:00–10:00 UTC Jan 19 10:00–15:00, 17:00–18:00 UTC Jan 20 09:00–11:00, 17:00–19:00, 22:00–23:00 UTC Jan 21 16:00–18:00 UTC Jan 22 07:00–09:00, 13:00–14:00 UTC Jan 23 06:00–13:00, 17:00–19:00, 22:00–24:00 UTC Jan 24 08:00–11:00, 17:00–18:00, 20:00–21:00 UTC Jan 25 02:00–03:00, 08:00–11:00, 17:00–20:00 UTC Jan 26 09:00–11:00, 20:00–21:00, 23:00–24:00 UTC Jan 27 10:00–11:00, 18:00–21:00 UTC Jan 28 09:00–11:00, 19:00–21:00 UTC Jan 29 11:00–12:00, 18:00–20:00 UTC Jan 30 10:00–12:00, 18:00–19:00 UTC Jan 31 05:00–08:00, 11:00–13:00, 17:00–24:00 UTC
February
Feb 1 18:00–20:00 UTC Feb 2 08:00–13:00, 20:00–21:00 UTC Feb 3 11:00–14:00, 20:00–21:00 UTC Feb 4 10:00–12:00, 19:00–20:00 UTC Feb 5 03:00–06:00, 10:00–13:00, 19:00–22:00 UTC Feb 6 02:00–04:00, 06:00–08:00, 11:00–12:00, 18:00–19:00 UTC Feb 7 10:00–17:00, 20:00–21:00 UTC Feb 8 01:00–02:00, 10:00–13:00, 18:00–20:00 UTC Feb 9 02:00–03:00, 10:00–14:00, 19:00–21:00 UTC Feb 10 10:00–13:00, 19:00–21:00 UTC Feb 11 05:00–11:00, 19:00–22:00 UTC Feb 12 10:00–12:00, 18:00–21:00 UTC Feb 13 01:00–03:00, 10:00–15:00, 17:00–19:00, 21:00–22:00 UTC Feb 14 09:00–11:00, 16:00–22:00 UTC Feb 15 09:00–12:00, 17:00–18:00, 23:00–24:00 UTC Feb 16 00:00–01:00, 10:00–12:00, 18:00–19:00 UTC Feb 17 06:00–07:00, 10:00–12:00, 19:00–21:00 UTC Feb 18 02:00–04:00, 09:00–10:00, 19:00–20:00 UTC Feb 19 10:00–12:00, 20:00–21:00 UTC Feb 20 10:00–12:00, 20:00–23:00 UTC Feb 21 09:00–11:00 UTC Feb 22 03:00–05:00, 09:00–11:00, 21:00–23:00 UTC Feb 23 10:00–12:00, 18:00–20:00 UTC Feb 24 09:00–12:00, 21:00–22:00 UTC Feb 25 11:00–15:00, 18:00–21:00 UTC Feb 26 06:00–08:00, 11:00–12:00, 19:00–20:00 UTC Feb 27 10:00–11:00 UTC Feb 28 01:00–02:00, 11:00–12:00, 18:00–21:00 UTC
March
Mar 1 10:00–13:00, 19:00–22:00 UTC Mar 2 10:00–12:00, 19:00–22:00 UTC Mar 3 12:00–13:00, 19:00–21:00 UTC Mar 4 10:00–13:00, 19:00–21:00 UTC Mar 5 08:00–10:00, 17:00–20:00 UTC Mar 6 10:00–11:00, 18:00–19:00 UTC Mar 7 09:00–11:00, 18:00–19:00 UTC Mar 8 00:00–02:00, 09:00–10:00, 19:00–21:00 UTC Mar 9 08:00–09:00, 18:00–19:00 UTC Mar 10 09:00–11:00 UTC Mar 12 06:00–07:00, 16:00–19:00 UTC Mar 13 06:00–07:00, 10:00–11:00 UTC Mar 14 10:00–11:00, 16:00–17:00, 23:00–24:00 UTC Mar 15 10:00–12:00, 17:00–18:00 UTC Mar 16 09:00–11:00, 19:00–21:00 UTC Mar 17 10:00–11:00 UTC Mar 18 10:00–12:00 UTC Mar 19 10:00–11:00 UTC Mar 20 01:00–02:00, 09:00–10:00, 13:00–14:00, 19:00–20:00 UTC Mar 21 10:00–11:00, 17:00–18:00, 22:00–23:00 UTC Mar 22 09:00–11:00, 17:00–22:00 UTC Mar 23 09:00–11:00, 18:00–20:00 UTC Mar 24 07:00–08:00, 15:00–16:00 UTC Mar 25 08:00–10:00 UTC Mar 26 07:00–08:00, 17:00–18:00 UTC Mar 27 10:00–16:00 UTC Mar 28 10:00–12:00, 19:00–20:00, 22:00–24:00 UTC Mar 29 04:00–07:00, 10:00–11:00, 17:00–18:00 UTC Mar 30 08:00–10:00, 17:00–19:00, 21:00–22:00 UTC Mar 31 09:00–12:00, 18:00–20:00 UTC
April
Apr 1 09:00–11:00, 17:00–18:00 UTC Apr 2 01:00–02:00, 05:00–06:00, 11:00–13:00 UTC Apr 3 05:00–06:00, 10:00–11:00 UTC Apr 4 09:00–13:00, 18:00–22:00 UTC Apr 5 11:00–12:00, 15:00–17:00, 20:00–21:00 UTC Apr 6 10:00–12:00, 18:00–20:00 UTC Apr 7 05:00–07:00, 10:00–11:00, 16:00–19:00 UTC Apr 8 10:00–12:00, 20:00–21:00 UTC Apr 9 10:00–11:00 UTC Apr 10 13:00–15:00 UTC Apr 11 11:00–12:00 UTC Apr 12 11:00–12:00, 19:00–21:00 UTC Apr 13 04:00–05:00, 11:00–12:00, 18:00–19:00 UTC Apr 14 04:00–05:00, 10:00–13:00, 17:00–18:00, 20:00–21:00 UTC Apr 15 06:00–07:00, 20:00–21:00 UTC Apr 16 05:00–06:00, 19:00–20:00 UTC Apr 17 11:00–14:00, 20:00–21:00 UTC Apr 18 10:00–15:00, 18:00–19:00, 22:00–24:00 UTC Apr 19 07:00–08:00, 11:00–12:00, 18:00–21:00 UTC Apr 20 09:00–11:00, 22:00–23:00 UTC Apr 21 03:00–05:00, 10:00–11:00, 17:00–18:00 UTC Apr 22 04:00–05:00, 11:00–13:00, 19:00–20:00 UTC Apr 24 00:00–01:00, 04:00–05:00, 18:00–19:00 UTC Apr 25 10:00–12:00 UTC Apr 26 11:00–13:00, 18:00–21:00 UTC Apr 27 18:00–19:00, 22:00–23:00 UTC Apr 28 03:00–04:00, 19:00–21:00 UTC Apr 29 03:00–06:00, 19:00–21:00 UTC Apr 30 04:00–05:00, 18:00–22:00 UTC
May
May 1 12:00–15:00, 19:00–20:00 UTC May 2 05:00–06:00 UTC May 3 11:00–15:00 UTC May 4 12:00–14:00, 23:00–24:00 UTC May 5 00:00–01:00, 09:00–10:00, 19:00–20:00 UTC May 6 08:00–09:00 UTC May 7 16:00–18:00 UTC May 8 13:00–14:00, 18:00–21:00 UTC May 9 06:00–08:00, 10:00–11:00, 14:00–15:00, 17:00–19:00 UTC May 10 02:00–05:00, 08:00–10:00, 17:00–18:00 UTC May 11 00:00–03:00, 09:00–11:00, 18:00–19:00, 21:00–22:00 UTC May 12 05:00–06:00, 10:00–11:00, 18:00–19:00 UTC May 13 01:00–02:00, 19:00–22:00 UTC May 14 03:00–04:00, 07:00–08:00, 19:00–21:00 UTC May 15 06:00–08:00, 22:00–23:00 UTC May 16 05:00–07:00, 23:00–24:00 UTC May 17 00:00–01:00, 12:00–14:00 UTC May 18 00:00–01:00, 07:00–10:00, 18:00–19:00 UTC May 19 02:00–03:00, 09:00–10:00, 19:00–21:00 UTC May 20 01:00–02:00, 06:00–07:00 UTC May 24 01:00–02:00 UTC May 28 05:00–07:00 UTC May 29 06:00–08:00 UTC May 31 00:00–07:00 UTC
June
Jun 1 13:00–18:00 UTC Jun 2 11:00–16:00 UTC Jun 3 05:00–10:00, 12:00–13:00 UTC Jun 4 04:00–06:00, 13:00–18:00, 20:00–22:00 UTC Jun 5 04:00–07:00, 11:00–12:00, 17:00–18:00 UTC Jun 6 04:00–06:00, 09:00–11:00, 18:00–19:00 UTC Jun 7 04:00–05:00, 12:00–17:00, 20:00–21:00 UTC Jun 8 07:00–09:00, 16:00–18:00 UTC Jun 9 09:00–10:00, 17:00–20:00 UTC Jun 10 05:00–10:00 UTC Jun 11 08:00–10:00, 16:00–17:00 UTC Jun 12 03:00–04:00, 06:00–07:00, 09:00–10:00, 20:00–22:00 UTC Jun 15 09:00–10:00, 16:00–17:00, 20:00–21:00 UTC Jun 16 03:00–04:00, 09:00–10:00, 17:00–19:00 UTC Jun 17 04:00–05:00, 09:00–11:00, 17:00–21:00 UTC Jun 18 11:00–12:00 UTC Jun 20 09:00–10:00 UTC Jun 21 05:00–08:00, 17:00–18:00 UTC Jun 22 04:00–06:00, 10:00–12:00, 17:00–19:00 UTC Jun 23 10:00–12:00, 16:00–18:00 UTC Jun 24 03:00–09:00 UTC Jun 25 06:00–10:00, 18:00–20:00 UTC Jun 26 03:00–04:00, 10:00–11:00, 18:00–19:00, 21:00–22:00 UTC Jun 27 06:00–10:00, 17:00–19:00, 23:00–24:00 UTC Jun 28 06:00–08:00, 11:00–12:00, 19:00–20:00, 23:00–24:00 UTC Jun 29 10:00–11:00, 17:00–19:00 UTC Jun 30 06:00–07:00, 10:00–11:00 UTC
July
Jul 1 09:00–11:00, 14:00–19:00 UTC Jul 2 05:00–07:00, 18:00–20:00 UTC Jul 3 09:00–10:00, 18:00–19:00, 22:00–23:00 UTC Jul 4 08:00–09:00, 18:00–21:00 UTC Jul 5 11:00–12:00, 23:00–24:00 UTC Jul 6 10:00–11:00, 17:00–20:00 UTC Jul 7 05:00–08:00, 10:00–11:00, 21:00–23:00 UTC Jul 8 04:00–05:00, 15:00–17:00 UTC Jul 9 06:00–07:00, 10:00–13:00, 19:00–20:00 UTC Jul 10 06:00–07:00, 13:00–15:00, 19:00–21:00 UTC Jul 11 02:00–03:00, 06:00–07:00, 09:00–14:00 UTC Jul 12 09:00–12:00, 16:00–17:00 UTC Jul 13 04:00–06:00, 10:00–11:00, 18:00–19:00 UTC Jul 14 06:00–08:00, 10:00–11:00, 15:00–17:00 UTC Jul 18 10:00–11:00, 15:00–16:00 UTC Jul 19 05:00–07:00, 09:00–10:00, 17:00–19:00 UTC Jul 20 11:00–12:00, 19:00–20:00 UTC Jul 21 11:00–12:00, 14:00–15:00 UTC Jul 22 13:00–14:00 UTC Jul 23 08:00–09:00, 20:00–22:00 UTC Jul 24 01:00–02:00, 05:00–07:00, 19:00–20:00, 22:00–23:00 UTC Jul 25 11:00–13:00, 18:00–24:00 UTC Jul 26 07:00–08:00, 13:00–14:00, 20:00–21:00 UTC Jul 27 14:00–15:00, 19:00–20:00 UTC