Most often in January, 30 days.
Highest follower count seen that year: 27,352.
January
Jan 2 04:00–06:00, 21:00–24:00 Jan 3 07:00–08:00 Jan 4 05:00–07:00, 21:00–23:00 Jan 5 21:00–23:00 Jan 6 06:00–07:00, 21:00–23:00 Jan 7 05:00–07:00, 21:00–23:00 Jan 8 05:00–08:00, 21:00–23:00 Jan 9 21:00–24:00 Jan 10 05:00–11:00 Jan 11 02:00–09:00, 21:00–22:00 Jan 12 21:00–23:00 Jan 13 06:00–07:00, 21:00–22:00 Jan 14 04:00–07:00, 22:00–23:00 Jan 15 06:00–09:00, 22:00–23:00 Jan 16 06:00–08:00, 22:00–24:00 Jan 17 00:00–01:00, 06:00–09:00 Jan 18 01:00–03:00, 06:00–09:00, 21:00–23:00 Jan 19 22:00–23:00 Jan 20 06:00–08:00, 21:00–23:00 Jan 21 05:00–07:00, 21:00–24:00 Jan 22 05:00–08:00, 21:00–24:00 Jan 23 05:00–06:00, 21:00–24:00 Jan 24 05:00–08:00 Jan 25 04:00–07:00, 22:00–24:00 Jan 26 05:00–08:00, 21:00–24:00 Jan 27 22:00–24:00 Jan 28 00:00–01:00, 06:00–07:00 Jan 29 22:00–24:00 Jan 30 05:00–08:00, 22:00–24:00 Jan 31 04:00–05:00
February
Feb 1 05:00–06:00, 17:00–19:00, 21:00–24:00 Feb 2 23:00–24:00 Feb 3 06:00–09:00, 21:00–24:00 Feb 4 06:00–07:00, 21:00–23:00 Feb 5 05:00–08:00, 22:00–24:00 Feb 6 06:00–08:00, 17:00–19:00, 21:00–23:00 Feb 7 05:00–08:00 Feb 8 06:00–07:00, 21:00–23:00 Feb 9 05:00–07:00, 21:00–24:00 Feb 10 00:00–02:00, 04:00–09:00, 21:00–23:00 Feb 11 22:00–24:00 Feb 12 06:00–08:00, 22:00–24:00 Feb 13 05:00–07:00, 21:00–24:00 Feb 14 06:00–07:00, 18:00–21:00 Feb 15 05:00–09:00, 21:00–24:00 Feb 16 06:00–08:00, 22:00–24:00 Feb 17 00:00–01:00 Feb 18 02:00–06:00, 22:00–24:00 Feb 19 05:00–09:00, 21:00–24:00 Feb 20 06:00–09:00 Feb 21 06:00–07:00 Feb 22 00:00–02:00, 05:00–08:00, 21:00–23:00 Feb 24 04:00–06:00, 21:00–23:00 Feb 25 04:00–07:00 Feb 26 05:00–07:00, 21:00–24:00 Feb 27 05:00–08:00 Feb 28 05:00–09:00
March
Mar 1 06:00–09:00, 21:00–23:00 Mar 4 05:00–08:00, 21:00–23:00 Mar 5 06:00–08:00 Mar 6 06:00–09:00 Mar 7 05:00–09:00 Mar 8 05:00–08:00, 21:00–23:00 Mar 10 05:00–09:00, 21:00–22:00 Mar 11 06:00–09:00 Mar 12 05:00–08:00, 21:00–22:00 Mar 13 06:00–07:00 Mar 14 04:00–07:00, 21:00–23:00 Mar 15 05:00–08:00, 21:00–23:00 Mar 16 05:00–06:00, 19:00–21:00 Mar 17 21:00–23:00 Mar 18 05:00–08:00, 21:00–23:00 Mar 19 05:00–07:00, 21:00–22:00 Mar 20 06:00–07:00, 19:00–22:00 Mar 21 05:00–08:00, 18:00–20:00 Mar 22 06:00–08:00 Mar 23 05:00–08:00 Mar 25 21:00–23:00 Mar 26 20:00–23:00 Mar 27 05:00–08:00, 20:00–23:00 Mar 28 05:00–08:00 Mar 29 05:00–09:00, 20:00–23:00 Mar 30 21:00–23:00 Mar 31 05:00–08:00, 21:00–23:00
April
Apr 1 05:00–06:00 Apr 2 04:00–07:00, 20:00–24:00 Apr 3 06:00–08:00 Apr 4 05:00–07:00, 21:00–24:00 Apr 6 05:00–09:00, 20:00–24:00 Apr 7 05:00–08:00 Apr 8 05:00–08:00, 21:00–23:00 Apr 10 05:00–08:00, 21:00–22:00 Apr 11 05:00–08:00, 18:00–21:00 Apr 12 21:00–23:00 Apr 13 05:00–08:00, 21:00–23:00 Apr 14 05:00–09:00, 20:00–23:00 Apr 15 21:00–22:00 Apr 16 05:00–09:00, 21:00–23:00 Apr 17 06:00–09:00, 19:00–22:00 Apr 18 06:00–08:00, 19:00–21:00 Apr 19 05:00–07:00, 20:00–21:00 Apr 20 05:00–08:00, 21:00–23:00 Apr 21 05:00–08:00 Apr 22 05:00–08:00, 21:00–23:00 Apr 23 06:00–07:00 Apr 24 21:00–23:00 Apr 25 06:00–08:00 Apr 27 05:00–08:00 Apr 28 06:00–07:00, 21:00–23:00 Apr 29 06:00–07:00, 22:00–23:00 Apr 30 05:00–07:00, 21:00–22:00
May
May 1 06:00–08:00 May 2 06:00–07:00, 22:00–24:00 May 3 21:00–23:00 May 4 05:00–08:00, 21:00–23:00 May 5 07:00–08:00 May 6 05:00–07:00, 21:00–23:00 May 7 05:00–08:00 May 8 06:00–07:00, 22:00–23:00 May 9 04:00–07:00 May 10 04:00–08:00 May 11 05:00–06:00 May 12 05:00–08:00 May 13 05:00–07:00, 21:00–24:00 May 14 05:00–08:00 May 15 06:00–09:00, 21:00–23:00 May 16 05:00–08:00 May 17 05:00–07:00 May 18 05:00–08:00 May 19 05:00–08:00, 21:00–23:00 May 20 05:00–08:00 May 21 06:00–08:00 May 22 06:00–08:00, 22:00–24:00 May 24 21:00–23:00 May 25 06:00–08:00 May 26 06:00–09:00, 21:00–23:00 May 27 06:00–08:00 May 28 06:00–09:00, 19:00–21:00 May 29 06:00–08:00, 22:00–23:00 May 30 05:00–06:00, 20:00–23:00 May 31 06:00–08:00
June
Jun 1 05:00–07:00 Jun 2 06:00–08:00, 22:00–23:00 Jun 3 06:00–07:00, 22:00–23:00 Jun 4 05:00–08:00, 22:00–24:00 Jun 5 06:00–07:00 Jun 6 06:00–10:00, 22:00–24:00 Jun 7 06:00–08:00 Jun 8 05:00–08:00, 22:00–23:00 Jun 9 06:00–08:00 Jun 10 05:00–07:00 Jun 11 06:00–08:00 Jun 12 04:00–05:00, 23:00–24:00 Jun 15 06:00–09:00 Jun 16 05:00–06:00, 21:00–23:00 Jun 18 05:00–08:00, 21:00–24:00 Jun 19 05:00–08:00, 21:00–24:00 Jun 20 05:00–06:00 Jun 21 06:00–08:00 Jun 22 05:00–08:00, 21:00–24:00 Jun 23 06:00–07:00 Jun 24 05:00–09:00, 23:00–24:00 Jun 25 00:00–01:00, 06:00–08:00 Jun 26 06:00–08:00, 22:00–23:00 Jun 28 05:00–08:00, 21:00–23:00 Jun 29 07:00–09:00, 22:00–24:00 Jun 30 06:00–08:00
July
Jul 1 05:00–07:00 Jul 2 05:00–06:00, 21:00–23:00 Jul 3 06:00–08:00 Jul 4 06:00–09:00 Jul 5 06:00–08:00 Jul 6 04:00–07:00, 21:00–23:00 Jul 7 05:00–08:00, 21:00–23:00 Jul 8 05:00–07:00, 21:00–23:00 Jul 9 05:00–08:00 Jul 10 00:00–01:00, 05:00–08:00, 22:00–24:00 Jul 11 07:00–09:00, 21:00–22:00 Jul 12 06:00–08:00, 22:00–24:00 Jul 13 00:00–01:00, 06:00–08:00 Jul 14 01:00–02:00, 06:00–09:00 Jul 16 04:00–06:00, 22:00–24:00 Jul 17 00:00–01:00 Jul 18 01:00–02:00, 06:00–09:00, 22:00–24:00 Jul 19 07:00–09:00 Jul 20 04:00–07:00 Jul 21 07:00–09:00 Jul 22 01:00–04:00, 13:00–16:00 Jul 23 00:00–02:00, 07:00–08:00 Jul 24 01:00–03:00, 05:00–08:00 Jul 26 05:00–08:00 Jul 27 02:00–03:00