Most often in March, 30 days.
Highest follower count seen that year: 5,577.
January
Jan 1 01:00–09:00 Jan 2 02:00–12:00, 23:00–24:00 Jan 3 00:00–09:00, 23:00–24:00 Jan 4 00:00–07:00 Jan 5 01:00–03:00, 05:00–08:00 Jan 6 01:00–03:00, 16:00–24:00 Jan 7 00:00–05:00, 23:00–24:00 Jan 8 00:00–02:00, 04:00–07:00 Jan 9 00:00–05:00, 23:00–24:00 Jan 10 00:00–01:00, 05:00–08:00 Jan 11 02:00–07:00, 22:00–24:00 Jan 12 00:00–06:00 Jan 13 00:00–06:00 Jan 14 02:00–03:00, 21:00–24:00 Jan 15 00:00–02:00, 04:00–06:00 Jan 16 00:00–01:00, 04:00–07:00 Jan 17 00:00–04:00 Jan 20 02:00–03:00 Jan 21 00:00–06:00, 23:00–24:00 Jan 22 00:00–04:00, 06:00–08:00 Jan 23 05:00–06:00, 21:00–23:00 Jan 24 04:00–08:00, 18:00–21:00 Jan 25 01:00–08:00, 19:00–20:00 Jan 26 20:00–23:00 Jan 28 04:00–06:00 Jan 29 04:00–07:00 Jan 30 00:00–04:00, 06:00–10:00, 21:00–23:00 Jan 31 00:00–01:00, 03:00–08:00, 15:00–22:00
February
Feb 1 00:00–01:00, 15:00–16:00, 20:00–23:00 Feb 2 01:00–06:00 Feb 3 06:00–07:00 Feb 4 23:00–24:00 Feb 5 00:00–01:00 Feb 6 02:00–03:00, 06:00–08:00, 23:00–24:00 Feb 7 01:00–09:00 Feb 8 00:00–06:00, 17:00–23:00 Feb 9 00:00–03:00, 21:00–23:00 Feb 10 00:00–04:00 Feb 11 00:00–02:00, 04:00–06:00 Feb 12 00:00–05:00, 23:00–24:00 Feb 13 00:00–04:00, 23:00–24:00 Feb 14 00:00–03:00, 05:00–13:00 Feb 15 01:00–03:00 Feb 17 00:00–06:00, 23:00–24:00 Feb 18 00:00–04:00, 18:00–22:00 Feb 19 02:00–05:00 Feb 20 02:00–09:00, 21:00–23:00 Feb 21 04:00–05:00, 10:00–12:00, 15:00–16:00 Feb 22 02:00–08:00, 13:00–19:00, 22:00–24:00 Feb 24 02:00–08:00, 13:00–19:00 Feb 26 03:00–10:00, 15:00–17:00, 19:00–20:00 Feb 27 22:00–24:00 Feb 28 00:00–01:00, 03:00–05:00, 07:00–08:00, 20:00–24:00
March
Mar 1 00:00–04:00 Mar 3 01:00–05:00, 07:00–08:00, 21:00–24:00 Mar 4 00:00–01:00, 03:00–06:00, 21:00–22:00 Mar 5 02:00–03:00 Mar 6 00:00–04:00, 23:00–24:00 Mar 7 00:00–02:00, 04:00–05:00, 21:00–24:00 Mar 8 00:00–03:00, 05:00–10:00, 23:00–24:00 Mar 9 00:00–02:00, 05:00–09:00 Mar 10 00:00–05:00 Mar 11 01:00–06:00 Mar 12 00:00–07:00 Mar 13 03:00–06:00, 08:00–09:00 Mar 14 04:00–09:00 Mar 15 00:00–06:00, 17:00–23:00 Mar 16 01:00–06:00, 22:00–24:00 Mar 17 00:00–08:00 Mar 18 23:00–24:00 Mar 19 00:00–03:00, 06:00–08:00 Mar 20 03:00–06:00 Mar 21 01:00–07:00, 16:00–19:00 Mar 22 03:00–11:00 Mar 23 03:00–09:00 Mar 24 02:00–03:00, 23:00–24:00 Mar 25 00:00–02:00, 22:00–23:00 Mar 26 02:00–05:00, 20:00–24:00 Mar 27 00:00–04:00, 21:00–23:00 Mar 28 00:00–03:00, 21:00–24:00 Mar 29 01:00–08:00, 21:00–24:00 Mar 30 00:00–07:00 Mar 31 00:00–07:00, 23:00–24:00
April
Apr 1 01:00–04:00, 15:00–21:00 Apr 2 01:00–06:00 Apr 3 03:00–04:00 Apr 4 02:00–03:00 Apr 5 00:00–05:00 Apr 6 22:00–23:00 Apr 7 03:00–07:00, 22:00–24:00 Apr 8 00:00–04:00 Apr 9 02:00–04:00, 07:00–08:00 Apr 10 00:00–06:00 Apr 11 06:00–08:00, 23:00–24:00 Apr 12 00:00–08:00 Apr 13 00:00–03:00, 06:00–08:00 Apr 14 01:00–08:00 Apr 15 01:00–06:00 Apr 16 01:00–09:00 Apr 17 02:00–05:00 Apr 18 03:00–10:00, 22:00–24:00 Apr 19 00:00–01:00, 05:00–06:00 Apr 22 02:00–06:00 Apr 23 03:00–05:00, 07:00–08:00, 22:00–24:00 Apr 24 00:00–01:00, 03:00–05:00 Apr 25 03:00–06:00, 18:00–19:00, 21:00–22:00 Apr 26 03:00–06:00, 22:00–23:00 Apr 28 18:00–20:00 Apr 29 02:00–03:00, 05:00–06:00 Apr 30 03:00–06:00, 17:00–23:00
May
May 1 00:00–04:00, 14:00–22:00 May 2 00:00–05:00 May 3 03:00–05:00, 17:00–20:00 May 4 01:00–02:00, 14:00–18:00, 23:00–24:00 May 5 00:00–04:00 May 11 00:00–04:00, 06:00–07:00 May 12 00:00–04:00 May 13 01:00–04:00, 22:00–24:00 May 14 00:00–01:00 May 15 01:00–04:00 May 16 03:00–05:00, 17:00–23:00 May 17 00:00–02:00, 18:00–24:00 May 18 00:00–07:00, 23:00–24:00 May 19 00:00–02:00 May 20 00:00–04:00 May 21 23:00–24:00 May 22 02:00–04:00 May 23 03:00–07:00 May 25 02:00–06:00 May 26 00:00–06:00 May 27 01:00–04:00, 06:00–08:00, 19:00–21:00 May 28 01:00–03:00, 14:00–20:00 May 29 02:00–07:00, 16:00–21:00 May 30 03:00–07:00, 13:00–18:00 May 31 10:00–14:00
June
Jun 1 16:00–22:00 Jun 2 01:00–05:00 Jun 3 02:00–06:00, 19:00–20:00 Jun 4 02:00–05:00, 22:00–24:00 Jun 5 00:00–02:00, 14:00–17:00, 19:00–22:00 Jun 6 01:00–05:00 Jun 7 01:00–06:00 Jun 8 00:00–06:00 Jun 9 02:00–06:00 Jun 10 03:00–08:00 Jun 11 02:00–05:00, 07:00–08:00, 17:00–19:00, 23:00–24:00 Jun 12 00:00–08:00 Jun 13 01:00–11:00 Jun 15 02:00–06:00 Jun 16 01:00–06:00 Jun 17 00:00–01:00, 04:00–09:00 Jun 18 01:00–04:00, 07:00–08:00 Jun 19 01:00–06:00 Jun 20 02:00–09:00 Jun 21 03:00–04:00 Jun 22 00:00–08:00 Jun 23 05:00–06:00 Jun 25 14:00–15:00 Jun 26 00:00–06:00 Jun 27 03:00–08:00, 11:00–15:00 Jun 28 04:00–08:00, 13:00–16:00 Jun 29 00:00–06:00, 14:00–15:00 Jun 30 02:00–03:00
July
Jul 1 23:00–24:00 Jul 2 00:00–08:00, 13:00–14:00 Jul 3 03:00–06:00, 12:00–15:00 Jul 4 01:00–02:00 Jul 5 02:00–08:00, 23:00–24:00 Jul 6 00:00–02:00, 21:00–24:00 Jul 7 00:00–07:00, 23:00–24:00 Jul 8 00:00–06:00, 23:00–24:00 Jul 9 00:00–04:00 Jul 10 00:00–04:00, 06:00–08:00, 23:00–24:00 Jul 11 00:00–03:00, 06:00–08:00 Jul 12 00:00–02:00 Jul 13 00:00–03:00 Jul 14 00:00–03:00, 09:00–12:00 Jul 16 01:00–04:00 Jul 17 05:00–08:00, 12:00–16:00 Jul 19 00:00–07:00 Jul 20 01:00–05:00, 13:00–17:00 Jul 21 01:00–05:00, 22:00–24:00 Jul 22 00:00–02:00, 04:00–05:00 Jul 23 01:00–06:00 Jul 24 01:00–02:00 Jul 25 03:00–07:00, 12:00–15:00, 23:00–24:00 Jul 26 00:00–05:00, 13:00–15:00, 23:00–24:00 Jul 27 00:00–02:00