Most often in March, 31 days.
Highest follower count seen that year: 1,522.
January
Jan 2 07:00–14:00 UTC Jan 3 07:00–11:00 UTC Jan 5 05:00–09:00, 14:00–16:00 UTC Jan 7 05:00–09:00, 12:00–17:00 UTC Jan 8 06:00–08:00, 11:00–12:00, 14:00–15:00 UTC Jan 9 05:00–09:00, 11:00–16:00 UTC Jan 10 06:00–10:00, 13:00–16:00 UTC Jan 11 07:00–11:00 UTC Jan 12 06:00–09:00, 12:00–16:00 UTC Jan 13 06:00–07:00, 09:00–13:00, 15:00–16:00 UTC Jan 14 07:00–15:00 UTC Jan 15 05:00–09:00, 13:00–16:00 UTC Jan 16 05:00–14:00 UTC Jan 17 07:00–11:00, 15:00–16:00 UTC Jan 18 07:00–12:00 UTC Jan 19 08:00–11:00 UTC Jan 21 06:00–10:00, 13:00–16:00 UTC Jan 22 08:00–12:00 UTC Jan 23 06:00–07:00, 11:00–12:00, 14:00–15:00 UTC Jan 26 06:00–09:00, 11:00–14:00 UTC Jan 27 06:00–14:00 UTC Jan 28 07:00–08:00, 11:00–15:00 UTC Jan 29 06:00–07:00, 11:00–12:00, 14:00–15:00 UTC Jan 30 06:00–10:00, 12:00–14:00 UTC Jan 31 06:00–07:00, 09:00–12:00, 14:00–15:00 UTC
February
Feb 1 08:00–13:00 UTC Feb 2 05:00–13:00 UTC Feb 3 08:00–11:00, 13:00–14:00 UTC Feb 5 10:00–13:00 UTC Feb 6 06:00–11:00, 13:00–16:00 UTC Feb 7 07:00–13:00 UTC Feb 8 08:00–12:00 UTC Feb 9 06:00–15:00 UTC Feb 10 07:00–10:00, 13:00–15:00 UTC Feb 11 11:00–13:00 UTC Feb 12 08:00–09:00, 12:00–14:00 UTC Feb 13 07:00–09:00, 14:00–16:00 UTC Feb 14 07:00–11:00, 13:00–14:00 UTC Feb 15 10:00–11:00 UTC Feb 16 10:00–11:00 UTC Feb 17 07:00–11:00, 14:00–15:00 UTC Feb 19 05:00–08:00, 10:00–11:00 UTC Feb 20 08:00–10:00, 14:00–15:00 UTC Feb 21 06:00–07:00, 09:00–15:00 UTC Feb 23 07:00–11:00, 13:00–15:00 UTC Feb 26 07:00–14:00 UTC Feb 27 07:00–08:00, 11:00–15:00 UTC Feb 28 07:00–14:00 UTC
March
Mar 1 08:00–11:00 UTC Mar 2 06:00–15:00 UTC Mar 3 08:00–12:00 UTC Mar 4 09:00–16:00 UTC Mar 5 06:00–15:00 UTC Mar 6 08:00–09:00, 14:00–15:00 UTC Mar 7 06:00–15:00 UTC Mar 8 08:00–09:00 UTC Mar 9 06:00–07:00, 09:00–15:00 UTC Mar 10 08:00–15:00 UTC Mar 11 07:00–15:00 UTC Mar 12 07:00–15:00 UTC Mar 13 06:00–11:00, 13:00–14:00 UTC Mar 14 08:00–15:00 UTC Mar 15 07:00–13:00 UTC Mar 16 07:00–14:00 UTC Mar 17 06:00–14:00 UTC Mar 18 07:00–08:00, 10:00–14:00 UTC Mar 19 08:00–09:00, 12:00–14:00 UTC Mar 20 06:00–15:00 UTC Mar 21 07:00–14:00 UTC Mar 22 06:00–15:00 UTC Mar 23 05:00–15:00 UTC Mar 24 06:00–11:00, 15:00–16:00 UTC Mar 25 07:00–10:00, 12:00–16:00 UTC Mar 26 08:00–14:00 UTC Mar 27 06:00–16:00 UTC Mar 28 07:00–15:00 UTC Mar 29 07:00–16:00 UTC Mar 30 07:00–15:00 UTC Mar 31 06:00–15:00 UTC
April
Apr 1 06:00–08:00, 11:00–15:00 UTC Apr 2 07:00–08:00, 10:00–11:00 UTC Apr 3 06:00–14:00 UTC Apr 4 05:00–10:00 UTC Apr 8 08:00–10:00, 12:00–15:00 UTC Apr 9 06:00–08:00, 10:00–15:00 UTC Apr 10 06:00–07:00, 10:00–13:00, 15:00–16:00 UTC Apr 11 06:00–13:00 UTC Apr 12 07:00–12:00 UTC Apr 13 07:00–10:00, 13:00–16:00 UTC Apr 14 07:00–08:00, 14:00–15:00 UTC Apr 15 08:00–09:00, 11:00–13:00 UTC Apr 16 06:00–15:00 UTC Apr 17 07:00–08:00 UTC Apr 18 05:00–12:00 UTC Apr 19 07:00–11:00 UTC Apr 20 09:00–13:00, 15:00–16:00 UTC Apr 21 06:00–07:00, 11:00–13:00 UTC Apr 22 10:00–13:00 UTC Apr 23 11:00–16:00 UTC Apr 24 07:00–15:00 UTC Apr 25 08:00–14:00 UTC Apr 26 07:00–12:00 UTC Apr 27 06:00–07:00, 10:00–12:00, 14:00–15:00 UTC Apr 28 06:00–08:00, 12:00–14:00 UTC Apr 29 06:00–07:00, 11:00–15:00 UTC Apr 30 07:00–08:00, 10:00–15:00 UTC
May
May 1 15:00–16:00 UTC May 2 06:00–07:00 UTC May 3 09:00–14:00 UTC May 4 06:00–16:00 UTC May 5 11:00–15:00 UTC May 6 08:00–09:00, 11:00–14:00 UTC May 7 06:00–10:00, 13:00–14:00 UTC May 8 07:00–09:00, 11:00–15:00 UTC May 9 07:00–08:00, 10:00–11:00, 14:00–15:00 UTC May 11 08:00–15:00 UTC May 12 10:00–14:00 UTC May 13 06:00–09:00, 14:00–15:00 UTC May 14 13:00–15:00 UTC May 16 08:00–15:00 UTC May 17 07:00–12:00 UTC May 18 06:00–09:00 UTC May 19 09:00–16:00 UTC May 20 07:00–08:00, 11:00–12:00, 14:00–15:00 UTC May 22 05:00–07:00, 09:00–16:00 UTC May 23 05:00–14:00 UTC May 26 06:00–12:00, 14:00–16:00 UTC May 27 05:00–09:00, 11:00–15:00 UTC May 28 10:00–15:00 UTC May 29 10:00–13:00 UTC May 30 07:00–15:00 UTC May 31 06:00–07:00, 09:00–10:00 UTC
June
Jun 1 06:00–09:00, 11:00–14:00 UTC Jun 2 05:00–14:00 UTC Jun 3 07:00–08:00, 10:00–11:00, 14:00–15:00 UTC Jun 4 05:00–10:00, 13:00–15:00 UTC Jun 5 08:00–14:00 UTC Jun 6 07:00–08:00, 11:00–15:00 UTC Jun 8 05:00–11:00, 13:00–16:00 UTC Jun 9 09:00–10:00, 12:00–16:00 UTC Jun 10 06:00–07:00, 14:00–15:00 UTC Jun 11 07:00–16:00 UTC Jun 12 07:00–08:00, 10:00–15:00 UTC Jun 13 07:00–08:00, 11:00–16:00 UTC Jun 15 06:00–15:00 UTC Jun 16 05:00–07:00, 09:00–15:00 UTC Jun 17 06:00–11:00 UTC Jun 19 06:00–07:00, 11:00–13:00 UTC Jun 20 10:00–11:00 UTC Jun 22 06:00–07:00, 11:00–13:00 UTC Jun 23 07:00–14:00 UTC Jun 24 06:00–15:00 UTC Jun 27 06:00–07:00, 11:00–12:00, 14:00–16:00 UTC Jun 29 10:00–16:00 UTC Jun 30 07:00–08:00, 15:00–16:00 UTC
July
Jul 1 08:00–14:00 UTC Jul 2 08:00–11:00 UTC Jul 3 06:00–08:00, 11:00–12:00, 15:00–16:00 UTC