Most often in August, 31 days.
Highest follower count seen that year: 10,963.
July
Jul 29 02:00–07:00, 12:00–16:00 UTC Jul 30 05:00–09:00, 11:00–16:00 UTC Jul 31 02:00–07:00, 11:00–15:00 UTC
August
Aug 1 02:00–07:00, 11:00–15:00 UTC Aug 2 02:00–07:00, 11:00–16:00 UTC Aug 3 03:00–07:00, 11:00–16:00 UTC Aug 4 02:00–06:00, 11:00–16:00 UTC Aug 5 06:00–07:00, 10:00–16:00 UTC Aug 6 11:00–14:00 UTC Aug 7 02:00–07:00, 12:00–16:00 UTC Aug 8 04:00–08:00, 11:00–17:00 UTC Aug 9 04:00–08:00, 11:00–17:00 UTC Aug 10 04:00–08:00, 13:00–17:00 UTC Aug 11 04:00–08:00, 10:00–16:00 UTC Aug 12 10:00–15:00 UTC Aug 13 04:00–07:00, 12:00–16:00 UTC Aug 14 04:00–08:00, 12:00–17:00 UTC Aug 15 04:00–08:00, 11:00–18:00 UTC Aug 16 03:00–07:00, 15:00–17:00 UTC Aug 17 03:00–08:00, 10:00–17:00 UTC Aug 18 03:00–08:00, 10:00–17:00 UTC Aug 19 03:00–08:00, 11:00–17:00 UTC Aug 20 03:00–08:00 UTC Aug 21 04:00–08:00, 11:00–16:00 UTC Aug 22 03:00–06:00, 10:00–16:00 UTC Aug 23 04:00–08:00, 11:00–16:00 UTC Aug 24 03:00–08:00, 11:00–17:00 UTC Aug 25 04:00–08:00, 14:00–16:00 UTC Aug 26 06:00–08:00, 11:00–16:00 UTC Aug 27 03:00–07:00 UTC Aug 28 04:00–08:00, 10:00–16:00 UTC Aug 29 04:00–07:00, 12:00–17:00 UTC Aug 30 04:00–08:00, 11:00–16:00 UTC Aug 31 03:00–08:00, 10:00–17:00 UTC
September
Sep 1 02:00–08:00, 12:00–15:00 UTC Sep 2 10:00–17:00 UTC Sep 3 02:00–07:00 UTC Sep 4 03:00–08:00, 11:00–16:00 UTC Sep 5 03:00–06:00, 11:00–15:00 UTC Sep 6 02:00–08:00, 12:00–16:00 UTC Sep 7 03:00–09:00, 13:00–16:00 UTC Sep 8 03:00–07:00, 10:00–16:00 UTC Sep 9 03:00–07:00, 11:00–16:00 UTC Sep 10 01:00–06:00 UTC Sep 11 02:00–08:00 UTC Sep 12 02:00–07:00, 11:00–16:00 UTC Sep 13 04:00–07:00, 11:00–17:00 UTC Sep 14 02:00–07:00, 12:00–14:00 UTC Sep 15 03:00–07:00, 11:00–16:00 UTC Sep 16 02:00–07:00 UTC Sep 17 03:00–07:00 UTC Sep 18 02:00–07:00, 11:00–16:00 UTC Sep 19 02:00–07:00, 13:00–17:00 UTC Sep 20 03:00–07:00, 11:00–17:00 UTC Sep 21 03:00–08:00, 11:00–16:00 UTC Sep 22 10:00–16:00 UTC Sep 23 04:00–06:00, 11:00–17:00 UTC Sep 24 02:00–06:00 UTC Sep 26 02:00–07:00, 11:00–15:00, 17:00–19:00 UTC Sep 27 03:00–07:00, 10:00–16:00 UTC Sep 28 03:00–07:00, 11:00–17:00 UTC Sep 29 03:00–05:00, 15:00–17:00 UTC Sep 30 01:00–07:00, 11:00–16:00 UTC
October
Oct 1 01:00–07:00 UTC Oct 2 02:00–07:00, 11:00–16:00 UTC Oct 3 02:00–07:00, 11:00–16:00 UTC Oct 4 02:00–07:00, 11:00–16:00 UTC Oct 5 04:00–08:00, 12:00–16:00 UTC Oct 6 03:00–07:00, 11:00–13:00 UTC Oct 7 02:00–07:00, 11:00–16:00 UTC Oct 8 01:00–07:00, 11:00–15:00 UTC Oct 9 02:00–07:00, 12:00–16:00 UTC Oct 10 02:00–07:00, 11:00–16:00 UTC Oct 11 02:00–07:00, 11:00–16:00 UTC Oct 12 03:00–08:00, 11:00–16:00 UTC Oct 13 04:00–08:00, 11:00–17:00 UTC Oct 14 03:00–08:00, 12:00–15:00 UTC Oct 15 02:00–06:00 UTC Oct 16 03:00–08:00, 11:00–16:00 UTC Oct 17 10:00–16:00 UTC Oct 18 02:00–07:00, 11:00–16:00 UTC Oct 19 02:00–08:00, 12:00–16:00 UTC Oct 20 01:00–07:00, 11:00–16:00 UTC Oct 21 02:00–08:00, 12:00–16:00 UTC Oct 22 02:00–07:00, 11:00–14:00 UTC Oct 23 02:00–07:00 UTC Oct 24 04:00–08:00, 11:00–15:00 UTC Oct 25 01:00–07:00, 11:00–16:00 UTC Oct 26 02:00–07:00, 14:00–16:00 UTC Oct 27 02:00–07:00, 11:00–15:00 UTC Oct 28 01:00–07:00, 11:00–16:00 UTC Oct 30 01:00–06:00, 11:00–15:00 UTC Oct 31 02:00–07:00, 11:00–13:00 UTC
November
Nov 1 02:00–07:00 UTC Nov 2 03:00–09:00, 12:00–14:00 UTC Nov 3 03:00–07:00, 11:00–17:00 UTC Nov 4 03:00–07:00, 11:00–14:00 UTC Nov 5 03:00–08:00 UTC Nov 6 02:00–07:00, 11:00–15:00 UTC Nov 7 02:00–08:00, 11:00–17:00 UTC Nov 8 02:00–07:00, 11:00–17:00 UTC Nov 9 02:00–08:00, 11:00–16:00 UTC Nov 10 02:00–08:00, 11:00–15:00 UTC Nov 11 02:00–08:00, 11:00–15:00 UTC Nov 13 02:00–07:00, 11:00–15:00 UTC Nov 14 03:00–08:00, 12:00–15:00 UTC Nov 15 02:00–08:00, 11:00–16:00 UTC Nov 16 02:00–08:00, 11:00–15:00 UTC Nov 17 02:00–07:00, 13:00–16:00 UTC Nov 18 02:00–08:00, 11:00–15:00 UTC Nov 20 03:00–08:00, 11:00–17:00 UTC Nov 21 03:00–07:00, 11:00–16:00 UTC Nov 22 02:00–05:00, 09:00–17:00 UTC Nov 23 02:00–08:00, 11:00–15:00 UTC Nov 24 02:00–07:00, 11:00–16:00 UTC Nov 25 02:00–07:00, 11:00–16:00 UTC Nov 27 02:00–08:00, 11:00–15:00 UTC Nov 28 02:00–06:00, 10:00–16:00 UTC Nov 29 02:00–08:00, 11:00–15:00 UTC Nov 30 03:00–08:00, 11:00–16:00 UTC
December
Dec 1 02:00–06:00 UTC Dec 5 03:00–08:00, 12:00–17:00 UTC Dec 6 03:00–07:00, 10:00–15:00 UTC Dec 7 03:00–08:00, 12:00–15:00 UTC Dec 8 02:00–07:00, 11:00–16:00 UTC Dec 9 02:00–07:00, 11:00–16:00 UTC Dec 11 03:00–07:00, 11:00–15:00 UTC Dec 12 03:00–05:00, 09:00–16:00 UTC Dec 13 03:00–07:00, 11:00–16:00 UTC Dec 14 03:00–07:00, 12:00–17:00 UTC Dec 15 02:00–08:00, 11:00–16:00 UTC Dec 16 03:00–08:00 UTC Dec 18 03:00–08:00, 11:00–16:00 UTC Dec 19 03:00–07:00, 11:00–13:00 UTC Dec 20 03:00–07:00, 11:00–15:00 UTC Dec 21 03:00–07:00, 11:00–15:00 UTC Dec 22 03:00–07:00, 10:00–15:00 UTC Dec 23 03:00–07:00 UTC Dec 24 03:00–07:00, 11:00–16:00 UTC Dec 25 03:00–06:00, 11:00–17:00 UTC Dec 26 04:00–08:00, 12:00–16:00 UTC Dec 27 04:00–07:00 UTC Dec 28 11:00–16:00 UTC Dec 29 02:00–04:00, 11:00–15:00 UTC Dec 30 02:00–07:00, 11:00–15:00 UTC Dec 31 02:00–06:00, 11:00–15:00 UTC