Most often in March, 31 days.
Highest follower count seen that year: 8,992.
January
Jan 8 06:00–09:00, 17:00–19:00 UTC Jan 9 05:00–08:00 UTC Jan 10 05:00–07:00, 15:00–18:00 UTC Jan 12 06:00–09:00, 11:00–12:00 UTC Jan 13 06:00–07:00 UTC Jan 14 04:00–06:00 UTC Jan 16 05:00–07:00, 15:00–17:00 UTC Jan 17 05:00–12:00, 15:00–16:00 UTC Jan 18 18:00–19:00 UTC Jan 19 04:00–05:00, 07:00–16:00 UTC Jan 20 06:00–12:00 UTC Jan 21 05:00–08:00, 11:00–14:00, 16:00–17:00, 19:00–20:00 UTC Jan 22 06:00–08:00, 13:00–21:00 UTC Jan 23 06:00–13:00 UTC Jan 24 06:00–07:00, 13:00–14:00 UTC Jan 25 05:00–06:00, 18:00–19:00 UTC Jan 26 04:00–07:00, 10:00–12:00, 17:00–18:00 UTC Jan 27 05:00–06:00, 09:00–10:00 UTC Jan 29 06:00–08:00, 11:00–15:00 UTC Jan 30 05:00–08:00, 11:00–12:00 UTC Jan 31 05:00–10:00, 14:00–16:00 UTC
February
Feb 1 06:00–08:00 UTC Feb 2 05:00–07:00, 11:00–12:00, 19:00–21:00 UTC Feb 3 05:00–08:00, 13:00–14:00, 18:00–19:00, 21:00–22:00 UTC Feb 4 11:00–15:00, 19:00–22:00 UTC Feb 5 05:00–06:00, 10:00–13:00, 20:00–22:00 UTC Feb 6 07:00–10:00, 20:00–22:00 UTC Feb 7 06:00–08:00, 19:00–24:00 UTC Feb 8 00:00–01:00, 07:00–08:00 UTC Feb 9 07:00–08:00, 15:00–16:00, 19:00–22:00 UTC Feb 10 06:00–08:00, 11:00–16:00, 19:00–22:00 UTC Feb 11 05:00–07:00, 11:00–12:00, 14:00–16:00, 19:00–22:00 UTC Feb 12 06:00–08:00, 11:00–13:00, 19:00–24:00 UTC Feb 13 06:00–08:00, 13:00–14:00, 19:00–24:00 UTC Feb 14 00:00–02:00, 06:00–08:00, 19:00–22:00 UTC Feb 15 02:00–04:00, 20:00–23:00 UTC Feb 16 06:00–09:00, 12:00–14:00, 18:00–23:00 UTC Feb 17 06:00–11:00, 13:00–15:00, 19:00–22:00 UTC Feb 18 05:00–06:00, 13:00–14:00, 18:00–21:00 UTC Feb 19 03:00–07:00, 14:00–15:00, 19:00–22:00 UTC Feb 20 19:00–23:00 UTC Feb 21 07:00–09:00, 17:00–21:00 UTC Feb 23 00:00–04:00, 09:00–11:00, 13:00–15:00, 23:00–24:00 UTC Feb 24 00:00–03:00, 09:00–14:00, 17:00–18:00 UTC Feb 25 02:00–07:00, 10:00–11:00, 17:00–18:00, 23:00–24:00 UTC Feb 26 00:00–04:00, 11:00–12:00, 15:00–16:00 UTC Feb 27 01:00–05:00, 07:00–15:00, 18:00–21:00 UTC Feb 28 02:00–06:00, 08:00–09:00, 13:00–15:00, 18:00–20:00 UTC
March
Mar 1 02:00–03:00, 06:00–09:00, 15:00–17:00, 20:00–21:00 UTC Mar 2 02:00–09:00, 12:00–13:00, 15:00–16:00, 19:00–24:00 UTC Mar 3 04:00–05:00, 07:00–08:00, 19:00–20:00 UTC Mar 4 04:00–10:00, 14:00–15:00, 19:00–22:00 UTC Mar 5 05:00–06:00, 13:00–14:00 UTC Mar 6 01:00–03:00, 12:00–13:00, 15:00–17:00, 19:00–20:00 UTC Mar 7 02:00–04:00, 08:00–09:00, 20:00–21:00 UTC Mar 8 06:00–07:00, 09:00–13:00, 18:00–20:00 UTC Mar 9 02:00–03:00, 05:00–08:00, 17:00–19:00, 22:00–24:00 UTC Mar 10 04:00–07:00 UTC Mar 11 18:00–19:00, 22:00–23:00 UTC Mar 12 06:00–08:00 UTC Mar 13 02:00–07:00, 09:00–13:00, 15:00–19:00 UTC Mar 14 01:00–07:00, 10:00–12:00, 16:00–17:00, 19:00–20:00, 22:00–23:00 UTC Mar 15 02:00–05:00, 18:00–20:00 UTC Mar 16 02:00–12:00, 17:00–24:00 UTC Mar 17 00:00–05:00, 09:00–12:00, 18:00–22:00 UTC Mar 18 03:00–09:00 UTC Mar 19 01:00–02:00, 04:00–05:00, 08:00–11:00, 16:00–20:00 UTC Mar 20 03:00–04:00, 07:00–08:00, 16:00–18:00, 20:00–24:00 UTC Mar 21 05:00–07:00 UTC Mar 22 03:00–06:00, 18:00–21:00 UTC Mar 23 03:00–04:00, 06:00–07:00, 17:00–19:00, 21:00–23:00 UTC Mar 24 05:00–08:00, 17:00–21:00 UTC Mar 25 00:00–01:00, 05:00–13:00, 19:00–21:00 UTC Mar 26 02:00–04:00, 06:00–11:00, 16:00–17:00 UTC Mar 27 03:00–06:00, 08:00–09:00 UTC Mar 28 02:00–06:00 UTC Mar 29 04:00–08:00, 12:00–13:00 UTC Mar 30 17:00–18:00, 21:00–22:00 UTC Mar 31 06:00–09:00, 18:00–21:00 UTC
April
Apr 1 06:00–07:00, 17:00–19:00 UTC Apr 2 03:00–04:00, 19:00–21:00 UTC Apr 4 03:00–07:00 UTC Apr 5 08:00–10:00 UTC Apr 6 04:00–06:00, 23:00–24:00 UTC Apr 7 00:00–01:00, 04:00–07:00, 09:00–10:00, 19:00–24:00 UTC Apr 8 00:00–04:00, 10:00–13:00 UTC Apr 9 00:00–02:00, 06:00–07:00, 15:00–16:00, 23:00–24:00 UTC Apr 10 00:00–04:00, 17:00–18:00 UTC Apr 11 05:00–08:00, 11:00–13:00, 18:00–19:00 UTC Apr 12 01:00–05:00, 07:00–08:00, 13:00–15:00 UTC Apr 13 01:00–07:00, 12:00–15:00, 22:00–23:00 UTC Apr 14 02:00–03:00, 05:00–07:00, 17:00–24:00 UTC Apr 15 12:00–13:00, 19:00–21:00 UTC Apr 16 02:00–07:00, 14:00–16:00 UTC Apr 17 06:00–07:00, 20:00–24:00 UTC Apr 18 04:00–05:00, 18:00–19:00 UTC Apr 19 05:00–07:00 UTC Apr 20 13:00–15:00, 17:00–19:00 UTC Apr 22 05:00–08:00, 19:00–20:00 UTC Apr 25 04:00–06:00 UTC Apr 28 01:00–02:00 UTC Apr 29 04:00–07:00, 13:00–14:00 UTC Apr 30 03:00–05:00 UTC
May
May 2 05:00–06:00 UTC May 3 07:00–09:00 UTC May 4 14:00–15:00 UTC May 5 02:00–04:00, 11:00–12:00 UTC May 8 18:00–19:00 UTC May 12 01:00–03:00 UTC May 15 19:00–21:00 UTC May 16 04:00–07:00, 09:00–16:00, 18:00–19:00 UTC May 17 06:00–10:00, 13:00–16:00, 20:00–23:00 UTC May 18 03:00–06:00, 12:00–14:00, 18:00–23:00 UTC May 19 05:00–07:00, 12:00–13:00, 16:00–23:00 UTC May 20 05:00–07:00, 16:00–21:00 UTC May 21 05:00–06:00, 10:00–11:00, 18:00–21:00 UTC May 22 04:00–13:00, 17:00–22:00 UTC May 23 05:00–07:00 UTC May 24 04:00–07:00, 11:00–12:00, 19:00–24:00 UTC May 25 01:00–02:00, 13:00–24:00 UTC May 26 04:00–07:00, 18:00–24:00 UTC May 27 06:00–07:00, 17:00–22:00 UTC May 28 08:00–09:00, 14:00–15:00, 17:00–22:00 UTC May 29 05:00–08:00, 17:00–19:00 UTC May 30 04:00–05:00, 18:00–21:00 UTC May 31 01:00–02:00, 16:00–17:00 UTC
June
Jun 1 04:00–07:00, 09:00–10:00, 12:00–13:00, 16:00–24:00 UTC Jun 2 06:00–07:00, 16:00–18:00 UTC Jun 3 08:00–09:00, 12:00–13:00, 17:00–19:00, 22:00–24:00 UTC Jun 4 06:00–07:00, 09:00–11:00, 17:00–22:00 UTC Jun 5 07:00–08:00, 12:00–14:00, 17:00–18:00 UTC Jun 6 02:00–03:00, 05:00–07:00 UTC Jun 7 21:00–22:00 UTC Jun 8 08:00–09:00, 16:00–19:00, 23:00–24:00 UTC Jun 10 05:00–08:00, 19:00–20:00 UTC Jun 11 02:00–03:00, 06:00–10:00, 14:00–15:00, 17:00–24:00 UTC Jun 12 06:00–13:00, 18:00–23:00 UTC Jun 13 07:00–09:00, 11:00–12:00, 15:00–16:00 UTC Jun 15 05:00–07:00, 09:00–11:00, 17:00–22:00 UTC Jun 16 05:00–07:00, 21:00–24:00 UTC Jun 17 00:00–01:00, 06:00–08:00, 15:00–17:00, 20:00–21:00 UTC Jun 18 05:00–07:00, 12:00–14:00, 17:00–21:00 UTC Jun 19 03:00–06:00, 10:00–11:00, 13:00–17:00, 19:00–22:00 UTC Jun 20 04:00–07:00, 09:00–13:00, 15:00–16:00 UTC Jun 21 06:00–07:00, 11:00–12:00, 15:00–19:00 UTC Jun 22 05:00–07:00, 10:00–13:00, 15:00–20:00 UTC Jun 23 06:00–08:00, 18:00–22:00 UTC Jun 24 11:00–12:00, 17:00–19:00 UTC Jun 25 06:00–08:00, 13:00–14:00, 16:00–22:00 UTC Jun 26 07:00–09:00, 12:00–13:00, 17:00–23:00 UTC Jun 27 15:00–19:00 UTC Jun 28 18:00–19:00 UTC Jun 29 09:00–10:00, 16:00–22:00 UTC Jun 30 07:00–08:00, 15:00–17:00, 19:00–23:00 UTC
July
Jul 1 07:00–09:00, 12:00–14:00, 16:00–22:00 UTC Jul 2 06:00–10:00, 13:00–20:00, 22:00–23:00 UTC Jul 3 06:00–07:00, 17:00–18:00, 20:00–24:00 UTC Jul 4 00:00–01:00, 14:00–15:00, 17:00–19:00, 21:00–24:00 UTC Jul 5 09:00–13:00, 19:00–21:00 UTC Jul 6 08:00–09:00, 19:00–22:00 UTC Jul 7 06:00–08:00, 10:00–11:00, 19:00–24:00 UTC Jul 8 06:00–08:00, 10:00–12:00, 15:00–18:00, 20:00–23:00 UTC Jul 9 04:00–07:00, 17:00–23:00 UTC Jul 10 08:00–09:00, 11:00–13:00, 16:00–21:00 UTC Jul 11 17:00–19:00 UTC Jul 12 09:00–10:00, 15:00–17:00 UTC Jul 13 08:00–09:00, 17:00–20:00, 22:00–23:00 UTC Jul 14 06:00–08:00, 10:00–11:00, 13:00–15:00, 17:00–19:00 UTC Jul 15 11:00–12:00, 15:00–19:00 UTC Jul 16 16:00–18:00 UTC Jul 17 06:00–08:00, 13:00–15:00, 17:00–20:00 UTC Jul 18 07:00–08:00, 10:00–14:00 UTC Jul 19 10:00–11:00, 14:00–17:00 UTC Jul 20 06:00–08:00, 19:00–24:00 UTC Jul 21 13:00–23:00 UTC Jul 22 07:00–08:00, 15:00–16:00, 18:00–23:00 UTC Jul 23 18:00–24:00 UTC Jul 24 00:00–03:00, 08:00–13:00, 18:00–22:00 UTC Jul 26 20:00–21:00 UTC Jul 27 07:00–09:00, 17:00–18:00, 19:00–20:00 UTC