Most often in March, 31 days.
Highest follower count seen that year: 19,103.
January
Jan 1 00:00–08:00, 18:00–21:00 Jan 2 00:00–08:00 Jan 3 18:00–24:00 Jan 4 00:00–06:00, 23:00–24:00 Jan 5 00:00–07:00, 16:00–21:00 Jan 6 22:00–24:00 Jan 7 00:00–05:00 Jan 8 04:00–07:00 Jan 9 01:00–03:00 Jan 10 03:00–05:00, 20:00–24:00 Jan 11 00:00–06:00, 20:00–24:00 Jan 12 00:00–07:00, 19:00–24:00 Jan 13 03:00–06:00, 19:00–22:00 Jan 14 03:00–06:00, 21:00–24:00 Jan 15 01:00–04:00, 15:00–19:00 Jan 16 01:00–06:00 Jan 17 04:00–06:00, 23:00–24:00 Jan 18 00:00–06:00 Jan 19 01:00–06:00, 15:00–20:00 Jan 20 02:00–06:00, 18:00–19:00, 21:00–24:00 Jan 21 00:00–05:00, 23:00–24:00 Jan 22 00:00–05:00, 18:00–24:00 Jan 23 00:00–06:00, 23:00–24:00 Jan 24 00:00–03:00, 05:00–06:00, 21:00–24:00 Jan 25 00:00–07:00 Jan 26 00:00–05:00 Jan 27 20:00–24:00 Jan 28 00:00–06:00, 14:00–24:00 Jan 29 03:00–05:00 Jan 30 20:00–23:00 Jan 31 00:00–09:00, 17:00–20:00, 22:00–24:00
February
Feb 1 00:00–01:00, 03:00–10:00, 18:00–24:00 Feb 2 00:00–07:00 Feb 3 00:00–07:00, 22:00–24:00 Feb 4 00:00–05:00 Feb 5 00:00–06:00, 18:00–24:00 Feb 6 00:00–06:00 Feb 7 02:00–08:00, 22:00–24:00 Feb 8 00:00–02:00, 04:00–08:00, 21:00–23:00 Feb 9 00:00–01:00, 03:00–08:00, 22:00–24:00 Feb 10 02:00–08:00 Feb 11 02:00–07:00, 18:00–22:00 Feb 12 02:00–08:00, 20:00–24:00 Feb 13 02:00–05:00, 21:00–24:00 Feb 14 00:00–09:00, 20:00–24:00 Feb 15 00:00–09:00, 19:00–24:00 Feb 16 00:00–08:00 Feb 17 01:00–04:00, 18:00–20:00, 22:00–24:00 Feb 18 00:00–06:00 Feb 19 00:00–07:00, 16:00–19:00, 21:00–23:00 Feb 20 00:00–07:00, 22:00–24:00 Feb 21 00:00–08:00 Feb 22 05:00–08:00, 17:00–18:00, 20:00–24:00 Feb 23 00:00–02:00, 04:00–08:00, 22:00–24:00 Feb 24 00:00–05:00 Feb 25 04:00–07:00 Feb 26 03:00–07:00 Feb 27 01:00–09:00, 18:00–19:00 Feb 28 06:00–11:00
March
Mar 1 00:00–09:00, 18:00–24:00 Mar 2 00:00–10:00 Mar 3 06:00–08:00, 22:00–24:00 Mar 4 00:00–07:00, 15:00–17:00 Mar 5 01:00–02:00, 06:00–09:00, 17:00–19:00 Mar 6 00:00–01:00 Mar 7 21:00–22:00 Mar 8 00:00–10:00, 23:00–24:00 Mar 9 00:00–11:00 Mar 10 04:00–13:00, 23:00–24:00 Mar 11 00:00–09:00, 22:00–24:00 Mar 12 00:00–08:00 Mar 13 00:00–08:00, 15:00–24:00 Mar 14 02:00–07:00, 23:00–24:00 Mar 15 00:00–06:00, 14:00–24:00 Mar 16 01:00–08:00, 20:00–24:00 Mar 17 05:00–08:00, 21:00–22:00 Mar 18 00:00–10:00, 23:00–24:00 Mar 19 00:00–01:00, 04:00–07:00, 23:00–24:00 Mar 20 00:00–02:00, 05:00–09:00, 23:00–24:00 Mar 21 00:00–08:00 Mar 22 00:00–08:00, 18:00–24:00 Mar 23 00:00–01:00, 04:00–09:00, 19:00–24:00 Mar 24 00:00–09:00 Mar 25 00:00–02:00, 04:00–08:00 Mar 26 03:00–07:00, 21:00–24:00 Mar 27 00:00–06:00, 19:00–20:00, 22:00–24:00 Mar 28 00:00–08:00, 20:00–21:00, 23:00–24:00 Mar 29 00:00–05:00, 12:00–14:00, 16:00–19:00, 23:00–24:00 Mar 30 00:00–07:00 Mar 31 03:00–05:00
April
Apr 1 03:00–06:00, 16:00–24:00 Apr 2 00:00–06:00, 17:00–18:00, 22:00–24:00 Apr 3 00:00–07:00 Apr 4 11:00–13:00 Apr 5 02:00–08:00, 21:00–24:00 Apr 6 00:00–07:00, 22:00–24:00 Apr 7 03:00–06:00, 22:00–24:00 Apr 8 02:00–07:00, 17:00–18:00, 21:00–23:00 Apr 9 00:00–10:00 Apr 11 03:00–07:00, 20:00–24:00 Apr 12 00:00–08:00, 16:00–23:00 Apr 13 00:00–09:00, 22:00–24:00 Apr 14 00:00–06:00, 20:00–23:00 Apr 15 06:00–07:00, 21:00–23:00 Apr 16 00:00–07:00, 16:00–18:00, 21:00–24:00 Apr 17 00:00–07:00, 22:00–24:00 Apr 18 00:00–10:00, 22:00–24:00 Apr 19 00:00–01:00, 05:00–09:00, 17:00–18:00, 20:00–24:00 Apr 20 00:00–10:00, 20:00–21:00 Apr 21 00:00–09:00, 22:00–24:00 Apr 22 00:00–08:00 Apr 23 01:00–10:00, 20:00–23:00 Apr 24 03:00–09:00 Apr 25 03:00–09:00 Apr 26 00:00–09:00, 20:00–23:00 Apr 27 00:00–01:00, 03:00–09:00, 23:00–24:00 Apr 28 02:00–09:00 Apr 29 04:00–06:00, 23:00–24:00 Apr 30 00:00–10:00, 19:00–23:00
May
May 1 03:00–06:00, 16:00–24:00 May 2 00:00–08:00 May 3 00:00–08:00, 21:00–22:00 May 4 00:00–02:00, 05:00–10:00, 23:00–24:00 May 5 00:00–06:00, 18:00–22:00 May 6 00:00–12:00, 23:00–24:00 May 7 00:00–10:00, 18:00–19:00 May 8 05:00–07:00, 13:00–15:00, 17:00–23:00 May 9 00:00–01:00, 03:00–06:00, 16:00–18:00, 21:00–22:00 May 10 00:00–01:00, 04:00–08:00, 17:00–24:00 May 11 00:00–06:00, 14:00–23:00 May 12 02:00–06:00, 20:00–21:00 May 13 01:00–06:00, 21:00–24:00 May 14 01:00–05:00, 16:00–23:00 May 15 02:00–06:00, 19:00–23:00 May 16 01:00–07:00 May 17 15:00–16:00, 21:00–22:00 May 18 00:00–06:00 May 19 03:00–08:00, 16:00–24:00 May 20 00:00–07:00, 16:00–17:00 May 21 01:00–07:00, 17:00–24:00 May 22 02:00–06:00, 15:00–20:00 May 23 00:00–08:00, 14:00–19:00, 22:00–24:00 May 24 00:00–06:00, 17:00–19:00, 22:00–24:00 May 25 00:00–06:00 May 26 03:00–04:00, 23:00–24:00 May 27 00:00–01:00, 03:00–04:00, 23:00–24:00 May 28 00:00–07:00, 18:00–24:00 May 29 03:00–07:00 May 30 00:00–01:00
June
Jun 1 03:00–07:00, 22:00–24:00 Jun 2 00:00–04:00, 19:00–24:00 Jun 3 04:00–06:00, 18:00–19:00 Jun 4 21:00–24:00 Jun 5 00:00–08:00 Jun 6 04:00–08:00, 21:00–22:00 Jun 7 01:00–09:00, 23:00–24:00 Jun 8 00:00–01:00, 03:00–04:00 Jun 10 22:00–24:00 Jun 11 00:00–06:00, 21:00–23:00 Jun 12 05:00–08:00, 22:00–23:00 Jun 13 00:00–02:00, 04:00–09:00 Jun 15 01:00–07:00, 15:00–16:00 Jun 16 00:00–07:00 Jun 17 04:00–07:00, 20:00–24:00 Jun 18 02:00–07:00 Jun 19 00:00–06:00, 20:00–23:00 Jun 20 00:00–03:00, 15:00–17:00, 23:00–24:00 Jun 21 00:00–02:00, 21:00–24:00 Jun 22 00:00–08:00, 19:00–21:00 Jun 23 05:00–07:00 Jun 24 01:00–03:00 Jun 25 03:00–06:00, 21:00–23:00 Jun 26 03:00–08:00, 22:00–24:00 Jun 27 21:00–24:00 Jun 28 04:00–07:00, 21:00–24:00 Jun 29 00:00–01:00, 03:00–05:00 Jun 30 01:00–07:00, 21:00–23:00
July
Jul 1 01:00–05:00, 18:00–24:00 Jul 2 00:00–07:00, 18:00–24:00 Jul 3 00:00–08:00 Jul 4 03:00–06:00, 22:00–24:00 Jul 5 00:00–08:00, 17:00–21:00 Jul 6 00:00–01:00, 03:00–07:00 Jul 7 22:00–24:00 Jul 8 00:00–06:00, 21:00–22:00 Jul 9 00:00–05:00 Jul 10 22:00–24:00 Jul 11 00:00–02:00, 04:00–05:00 Jul 12 19:00–20:00 Jul 13 02:00–07:00, 23:00–24:00 Jul 14 00:00–01:00, 03:00–07:00 Jul 16 00:00–06:00, 15:00–18:00 Jul 17 04:00–07:00 Jul 18 04:00–05:00, 20:00–24:00 Jul 19 00:00–06:00, 19:00–21:00, 23:00–24:00 Jul 20 00:00–07:00, 23:00–24:00 Jul 21 00:00–06:00, 17:00–19:00 Jul 22 01:00–05:00, 20:00–24:00 Jul 23 01:00–02:00, 07:00–08:00 Jul 24 00:00–01:00, 05:00–09:00, 18:00–21:00 Jul 25 00:00–05:00, 23:00–24:00 Jul 26 00:00–02:00, 19:00–22:00, 23:00–24:00 Jul 27 00:00–02:00