Most often in January, 30 days.
Highest follower count seen that year: 2,113.
January
Jan 1 02:00–05:00 Jan 2 02:00–11:00 Jan 3 02:00–11:00 Jan 4 03:00–12:00 Jan 5 02:00–11:00 Jan 6 03:00–11:00 Jan 7 03:00–11:00 Jan 8 03:00–11:00 Jan 9 02:00–11:00 Jan 10 03:00–11:00 Jan 11 03:00–11:00 Jan 12 02:00–11:00 Jan 13 03:00–11:00 Jan 14 02:00–11:00 Jan 15 03:00–11:00 Jan 16 03:00–11:00 Jan 17 03:00–11:00 Jan 19 02:00–11:00 Jan 20 03:00–11:00 Jan 21 02:00–11:00 Jan 22 03:00–11:00 Jan 23 03:00–11:00 Jan 24 05:00–11:00 Jan 25 03:00–11:00 Jan 26 02:00–10:00 Jan 27 03:00–11:00 Jan 28 03:00–06:00, 10:00–11:00 Jan 29 03:00–08:00, 13:00–14:00 Jan 30 03:00–11:00 Jan 31 03:00–11:00
February
Feb 1 03:00–11:00 Feb 2 02:00–11:00 Feb 3 02:00–11:00 Feb 4 03:00–05:00, 09:00–11:00 Feb 5 02:00–06:00, 10:00–11:00 Feb 6 02:00–11:00 Feb 7 04:00–11:00 Feb 8 02:00–10:00 Feb 9 02:00–11:00 Feb 10 03:00–10:00 Feb 11 03:00–11:00 Feb 12 03:00–07:00 Feb 22 03:00–06:00, 08:00–11:00 Feb 23 02:00–06:00, 08:00–10:00 Feb 24 02:00–11:00 Feb 25 03:00–11:00 Feb 26 03:00–11:00 Feb 27 03:00–11:00 Feb 28 03:00–11:00
March
Mar 1 03:00–12:00 Mar 2 03:00–11:00 Mar 3 03:00–05:00, 08:00–11:00 Mar 4 03:00–11:00 Mar 5 03:00–11:00 Mar 6 03:00–04:00, 08:00–11:00 Mar 7 03:00–11:00 Mar 8 03:00–06:00, 08:00–11:00 Mar 9 05:00–11:00 Mar 10 02:00–10:00 Mar 11 03:00–10:00 Mar 12 03:00–10:00 Mar 13 03:00–10:00 Mar 14 03:00–10:00 Mar 16 02:00–09:00 Mar 17 02:00–11:00 Mar 18 03:00–11:00 Mar 19 04:00–05:00, 08:00–11:00 Mar 20 07:00–11:00 Mar 21 03:00–06:00, 08:00–10:00 Mar 22 02:00–10:00 Mar 23 03:00–09:00 Mar 24 02:00–11:00 Mar 25 02:00–10:00 Mar 26 03:00–05:00, 07:00–10:00 Mar 27 03:00–10:00 Mar 28 02:00–06:00, 08:00–10:00 Mar 29 04:00–11:00 Mar 30 02:00–04:00, 06:00–11:00 Mar 31 03:00–06:00, 08:00–11:00
April
Apr 1 03:00–10:00 Apr 2 02:00–11:00 Apr 3 03:00–11:00 Apr 4 02:00–05:00 Apr 6 02:00–04:00, 06:00–08:00, 10:00–11:00 Apr 7 03:00–09:00 Apr 8 02:00–07:00, 09:00–10:00 Apr 9 02:00–04:00, 08:00–10:00 Apr 10 02:00–06:00, 08:00–11:00 Apr 11 04:00–09:00 Apr 12 02:00–11:00 Apr 13 02:00–11:00 Apr 14 03:00–11:00 Apr 15 02:00–04:00, 06:00–10:00 Apr 16 03:00–11:00 Apr 17 02:00–03:00, 05:00–06:00, 08:00–09:00 Apr 18 03:00–11:00 Apr 19 06:00–09:00 Apr 20 02:00–05:00, 08:00–10:00 Apr 21 03:00–04:00, 08:00–11:00 Apr 22 02:00–11:00 Apr 23 03:00–06:00 Apr 24 06:00–11:00 Apr 25 03:00–10:00 Apr 26 03:00–05:00, 07:00–11:00 Apr 27 02:00–11:00 Apr 28 03:00–11:00 Apr 29 03:00–11:00 Apr 30 02:00–11:00
May
May 1 03:00–07:00 May 2 02:00–05:00 May 3 03:00–12:00 May 4 06:00–11:00 May 5 03:00–06:00, 09:00–11:00 May 6 02:00–11:00 May 7 02:00–11:00 May 8 05:00–11:00 May 12 02:00–11:00 May 13 02:00–11:00 May 14 04:00–11:00 May 15 02:00–13:00 May 16 04:00–11:00 May 17 01:00–11:00 May 18 02:00–13:00 May 19 06:00–11:00 May 20 03:00–11:00, 15:00–17:00 May 21 02:00–11:00 May 22 02:00–11:00, 13:00–16:00 May 23 03:00–11:00, 13:00–15:00 May 24 02:00–10:00, 14:00–16:00 May 25 02:00–10:00, 13:00–16:00 May 26 02:00–11:00, 13:00–17:00 May 27 02:00–11:00, 13:00–16:00 May 28 03:00–11:00, 13:00–15:00 May 29 02:00–11:00 May 30 02:00–11:00 May 31 02:00–11:00, 13:00–16:00
June
Jun 1 02:00–11:00, 13:00–16:00 Jun 2 02:00–11:00, 13:00–16:00 Jun 3 02:00–07:00, 09:00–11:00, 13:00–15:00 Jun 4 03:00–11:00, 13:00–16:00 Jun 5 03:00–08:00, 10:00–15:00 Jun 6 03:00–11:00 Jun 7 03:00–11:00, 14:00–17:00 Jun 8 03:00–11:00, 14:00–16:00 Jun 9 02:00–10:00, 14:00–15:00 Jun 10 02:00–11:00, 13:00–15:00 Jun 11 03:00–11:00, 13:00–16:00 Jun 12 02:00–11:00 Jun 13 05:00–12:00, 14:00–15:00 Jun 15 02:00–11:00, 13:00–15:00 Jun 16 04:00–10:00, 13:00–15:00 Jun 17 02:00–03:00, 05:00–11:00 Jun 18 03:00–09:00, 12:00–13:00 Jun 19 02:00–07:00 Jun 20 05:00–10:00 Jun 21 02:00–10:00 Jun 22 02:00–10:00 Jun 23 05:00–11:00, 13:00–14:00 Jun 24 02:00–11:00 Jun 25 03:00–11:00 Jun 26 02:00–10:00 Jun 27 02:00–07:00 Jun 28 04:00–05:00, 10:00–11:00 Jun 29 03:00–07:00, 09:00–11:00 Jun 30 02:00–03:00, 05:00–10:00
July
Jul 1 02:00–10:00 Jul 2 02:00–03:00, 05:00–06:00, 09:00–10:00 Jul 3 02:00–06:00, 09:00–10:00 Jul 4 02:00–10:00 Jul 5 05:00–11:00 Jul 6 02:00–11:00 Jul 7 02:00–11:00 Jul 8 02:00–11:00 Jul 9 02:00–11:00 Jul 10 04:00–10:00 Jul 11 03:00–04:00 Jul 13 02:00–11:00 Jul 14 03:00–06:00, 08:00–11:00 Jul 16 03:00–09:00 Jul 17 03:00–11:00 Jul 18 05:00–12:00 Jul 19 02:00–07:00 Jul 20 03:00–05:00, 09:00–12:00 Jul 21 03:00–06:00 Jul 22 02:00–10:00 Jul 23 05:00–11:00 Jul 24 09:00–10:00 Jul 26 03:00–06:00 Jul 27 06:00–07:00, 08:00–10:00