Most often in May, 28 days.
Highest follower count seen that year: 12,879.
January
Jan 4 00:00–03:00, 15:00–18:00 Jan 5 04:00–13:00, 20:00–24:00 Jan 6 00:00–01:00 Jan 7 00:00–06:00, 14:00–17:00 Jan 8 00:00–07:00 Jan 14 00:00–09:00 Jan 15 00:00–08:00 Jan 16 00:00–08:00 Jan 21 01:00–05:00 Jan 23 02:00–03:00 Jan 24 02:00–09:00 Jan 25 01:00–12:00 Jan 26 02:00–08:00 Jan 27 01:00–06:00 Jan 29 01:00–07:00 Jan 30 01:00–08:00
February
Feb 2 02:00–12:00 Feb 3 01:00–07:00 Feb 4 01:00–12:00 Feb 6 01:00–09:00 Feb 8 01:00–04:00 Feb 11 01:00–09:00 Feb 13 01:00–06:00 Feb 14 01:00–06:00 Feb 19 14:00–18:00 Feb 20 14:00–18:00 Feb 21 00:00–04:00, 14:00–18:00 Feb 23 02:00–10:00 Feb 28 20:00–24:00
March
Mar 1 00:00–13:00 Mar 2 01:00–12:00, 22:00–24:00 Mar 3 00:00–02:00, 20:00–24:00 Mar 4 00:00–08:00 Mar 6 01:00–08:00, 23:00–24:00 Mar 7 00:00–07:00, 21:00–24:00 Mar 8 00:00–09:00, 23:00–24:00 Mar 9 00:00–09:00 Mar 10 03:00–07:00, 23:00–24:00 Mar 11 00:00–05:00 Mar 12 16:00–21:00 Mar 13 21:00–24:00 Mar 14 00:00–02:00 Mar 15 16:00–19:00 Mar 17 23:00–24:00 Mar 18 00:00–05:00 Mar 19 00:00–07:00 Mar 20 02:00–08:00 Mar 23 18:00–19:00 Mar 24 14:00–18:00, 23:00–24:00 Mar 25 00:00–03:00, 14:00–19:00 Mar 26 19:00–23:00 Mar 27 02:00–05:00, 17:00–22:00 Mar 28 00:00–06:00, 20:00–24:00 Mar 29 00:00–05:00, 21:00–24:00 Mar 30 00:00–04:00, 21:00–24:00 Mar 31 00:00–04:00, 13:00–17:00, 23:00–24:00
April
Apr 1 00:00–06:00, 21:00–24:00 Apr 2 00:00–04:00, 21:00–24:00 Apr 3 00:00–08:00, 21:00–24:00 Apr 4 00:00–10:00 Apr 5 02:00–08:00, 22:00–23:00 Apr 6 01:00–06:00, 12:00–17:00, 21:00–22:00 Apr 7 00:00–08:00, 21:00–24:00 Apr 8 00:00–10:00, 21:00–24:00 Apr 9 00:00–06:00 Apr 10 21:00–24:00 Apr 11 00:00–01:00, 04:00–06:00, 21:00–24:00 Apr 12 00:00–05:00, 21:00–24:00 Apr 13 00:00–08:00, 21:00–24:00 Apr 14 00:00–06:00, 21:00–24:00 Apr 15 00:00–02:00, 21:00–24:00 Apr 16 00:00–05:00, 22:00–23:00 Apr 18 21:00–24:00 Apr 19 00:00–04:00 Apr 21 21:00–24:00 Apr 22 00:00–05:00, 21:00–24:00 Apr 23 00:00–02:00, 21:00–24:00 Apr 24 00:00–05:00, 22:00–24:00 Apr 25 00:00–04:00 Apr 27 21:00–24:00 Apr 28 00:00–04:00, 07:00–09:00, 21:00–24:00 Apr 29 00:00–07:00, 21:00–23:00 Apr 30 00:00–03:00, 21:00–24:00
May
May 1 00:00–05:00, 21:00–24:00 May 2 00:00–06:00, 21:00–24:00 May 3 00:00–04:00, 11:00–16:00 May 6 21:00–24:00 May 7 00:00–05:00, 23:00–24:00 May 8 00:00–04:00, 21:00–24:00 May 9 00:00–03:00, 21:00–24:00 May 10 00:00–03:00, 22:00–24:00 May 11 00:00–05:00 May 12 22:00–24:00 May 13 00:00–06:00 May 14 22:00–24:00 May 15 00:00–08:00, 23:00–24:00 May 16 00:00–08:00 May 18 00:00–07:00, 22:00–24:00 May 19 00:00–09:00, 22:00–24:00 May 20 00:00–10:00, 22:00–24:00 May 21 00:00–09:00, 22:00–24:00 May 22 00:00–09:00 May 23 22:00–24:00 May 24 00:00–10:00, 23:00–24:00 May 25 00:00–06:00, 22:00–24:00 May 26 00:00–10:00, 22:00–24:00 May 27 00:00–09:00, 22:00–24:00 May 28 00:00–07:00 May 29 01:00–08:00, 22:00–24:00 May 30 00:00–11:00 May 31 00:00–09:00
June
Jun 5 23:00–24:00 Jun 6 00:00–09:00 Jun 7 00:00–05:00, 11:00–17:00 Jun 8 00:00–15:00, 22:00–24:00 Jun 9 00:00–10:00, 22:00–24:00 Jun 10 00:00–06:00 Jun 11 05:00–09:00 Jun 12 00:00–06:00, 22:00–24:00 Jun 13 00:00–04:00 Jun 14 00:00–09:00 Jun 15 05:00–10:00 Jun 16 22:00–24:00 Jun 17 00:00–09:00, 22:00–24:00 Jun 18 00:00–05:00, 22:00–24:00 Jun 19 00:00–04:00 Jun 21 22:00–24:00 Jun 22 00:00–07:00 Jun 23 22:00–24:00 Jun 24 00:00–07:00 Jun 25 22:00–24:00 Jun 26 00:00–08:00, 22:00–24:00 Jun 27 00:00–07:00 Jun 28 23:00–24:00 Jun 29 00:00–07:00, 23:00–24:00 Jun 30 00:00–07:00
July
Jul 2 01:00–11:00, 23:00–24:00 Jul 3 00:00–09:00 Jul 4 00:00–10:00 Jul 8 23:00–24:00 Jul 9 00:00–08:00, 23:00–24:00 Jul 10 00:00–05:00 Jul 11 23:00–24:00 Jul 12 00:00–07:00, 22:00–24:00 Jul 13 00:00–02:00 Jul 14 15:00–18:00, 23:00–24:00 Jul 15 00:00–06:00 Jul 19 23:00–24:00 Jul 20 00:00–06:00 Jul 22 03:00–12:00