Most often in March, 30 days.
Highest follower count seen that year: 6,923.
January
Jan 1 00:00–04:00 Jan 2 01:00–05:00 Jan 3 01:00–05:00, 15:00–19:00 Jan 4 01:00–03:00, 19:00–24:00 Jan 5 16:00–19:00 Jan 6 00:00–01:00 Jan 8 00:00–03:00 Jan 9 17:00–19:00 Jan 11 19:00–24:00 Jan 12 03:00–04:00, 20:00–23:00 Jan 13 01:00–03:00 Jan 14 00:00–03:00 Jan 15 16:00–18:00 Jan 20 00:00–03:00 Jan 21 04:00–09:00 Jan 22 04:00–09:00 Jan 23 05:00–10:00 Jan 24 00:00–03:00, 19:00–23:00 Jan 25 19:00–20:00, 22:00–23:00 Jan 26 16:00–20:00 Jan 27 00:00–02:00
February
Feb 1 15:00–18:00, 20:00–23:00 Feb 2 00:00–01:00, 17:00–20:00 Feb 3 01:00–03:00, 17:00–19:00, 23:00–24:00 Feb 4 00:00–03:00, 17:00–20:00, 23:00–24:00 Feb 5 00:00–03:00, 17:00–20:00 Feb 6 00:00–03:00 Feb 7 00:00–05:00 Feb 8 00:00–02:00, 16:00–23:00 Feb 9 00:00–02:00 Feb 10 00:00–05:00 Feb 11 00:00–06:00 Feb 12 15:00–18:00, 20:00–21:00 Feb 13 01:00–02:00, 19:00–23:00 Feb 14 01:00–02:00, 19:00–22:00 Feb 15 00:00–04:00, 06:00–08:00, 20:00–23:00 Feb 16 01:00–02:00, 19:00–23:00 Feb 17 00:00–02:00, 18:00–23:00 Feb 20 02:00–09:00 Feb 21 03:00–07:00 Feb 22 15:00–24:00 Feb 23 00:00–03:00, 15:00–23:00 Feb 24 20:00–23:00 Feb 25 01:00–03:00 Feb 26 01:00–07:00, 19:00–23:00 Feb 27 01:00–02:00, 16:00–23:00 Feb 28 00:00–03:00, 19:00–23:00
March
Mar 1 01:00–05:00, 17:00–24:00 Mar 2 00:00–01:00 Mar 3 00:00–05:00, 21:00–23:00 Mar 4 16:00–17:00, 23:00–24:00 Mar 5 02:00–06:00 Mar 6 00:00–03:00, 08:00–10:00 Mar 7 20:00–23:00 Mar 8 00:00–05:00, 15:00–23:00 Mar 9 14:00–19:00 Mar 10 19:00–24:00 Mar 11 00:00–02:00, 23:00–24:00 Mar 12 00:00–03:00 Mar 13 15:00–20:00 Mar 14 00:00–04:00, 19:00–23:00 Mar 15 01:00–05:00, 16:00–23:00 Mar 16 00:00–02:00 Mar 17 01:00–03:00 Mar 18 16:00–19:00, 23:00–24:00 Mar 19 00:00–02:00 Mar 20 05:00–11:00 Mar 21 04:00–10:00 Mar 22 03:00–08:00, 19:00–22:00 Mar 24 04:00–08:00 Mar 25 23:00–24:00 Mar 26 00:00–07:00 Mar 27 05:00–06:00 Mar 28 04:00–07:00 Mar 29 04:00–08:00, 20:00–23:00 Mar 30 02:00–04:00 Mar 31 20:00–22:00
April
Apr 1 01:00–04:00 Apr 2 01:00–07:00 Apr 3 05:00–11:00 Apr 4 04:00–09:00 Apr 5 05:00–09:00, 20:00–23:00 Apr 7 03:00–07:00 Apr 9 00:00–07:00 Apr 11 03:00–07:00 Apr 12 05:00–12:00 Apr 13 13:00–16:00 Apr 14 12:00–16:00, 20:00–22:00 Apr 15 13:00–19:00 Apr 18 20:00–24:00 Apr 19 18:00–23:00 Apr 20 01:00–05:00 Apr 21 17:00–20:00 Apr 22 02:00–09:00 Apr 23 02:00–10:00 Apr 24 01:00–02:00 Apr 25 22:00–24:00 Apr 26 00:00–07:00, 19:00–23:00 Apr 27 01:00–04:00 Apr 29 02:00–04:00, 11:00–12:00, 14:00–16:00 Apr 30 17:00–21:00
May
May 1 19:00–23:00 May 2 14:00–17:00 May 3 00:00–02:00, 21:00–23:00 May 9 19:00–24:00 May 10 02:00–03:00, 19:00–22:00 May 12 12:00–15:00 May 13 12:00–17:00 May 14 16:00–23:00 May 15 01:00–03:00, 18:00–22:00 May 16 21:00–24:00 May 17 01:00–04:00, 15:00–17:00, 20:00–22:00 May 18 18:00–22:00 May 19 01:00–03:00 May 23 21:00–23:00 May 24 01:00–03:00, 18:00–24:00 May 25 02:00–04:00, 17:00–20:00 May 26 00:00–03:00 May 27 03:00–10:00 May 28 15:00–20:00 May 29 01:00–05:00 May 30 15:00–18:00, 20:00–24:00 May 31 18:00–23:00
June
Jun 4 20:00–24:00 Jun 5 02:00–03:00 Jun 6 19:00–24:00 Jun 7 02:00–04:00, 19:00–23:00 Jun 8 16:00–18:00 Jun 10 03:00–11:00 Jun 11 16:00–23:00 Jun 12 00:00–03:00, 17:00–19:00 Jun 13 01:00–03:00 Jun 15 02:00–06:00, 15:00–17:00, 21:00–22:00 Jun 19 15:00–22:00 Jun 20 02:00–04:00, 16:00–19:00, 21:00–24:00 Jun 21 20:00–24:00 Jun 22 02:00–04:00, 20:00–22:00 Jun 24 15:00–23:00 Jun 25 00:00–03:00, 16:00–19:00, 23:00–24:00 Jun 26 00:00–03:00, 17:00–18:00, 20:00–23:00 Jun 27 20:00–23:00 Jun 28 02:00–07:00, 15:00–22:00 Jun 29 16:00–19:00, 23:00–24:00 Jun 30 00:00–04:00, 14:00–17:00
July
Jul 2 15:00–19:00 Jul 3 01:00–05:00, 19:00–21:00 Jul 4 02:00–04:00 Jul 5 17:00–23:00 Jul 6 02:00–05:00, 20:00–24:00 Jul 7 02:00–06:00, 19:00–22:00 Jul 8 01:00–03:00, 16:00–18:00, 20:00–24:00 Jul 9 01:00–05:00, 16:00–19:00, 21:00–24:00 Jul 11 02:00–09:00 Jul 12 02:00–06:00 Jul 13 02:00–07:00 Jul 14 05:00–10:00, 21:00–23:00 Jul 15 00:00–02:00, 16:00–22:00 Jul 16 01:00–04:00, 23:00–24:00 Jul 17 00:00–04:00, 16:00–18:00 Jul 18 05:00–11:00 Jul 19 00:00–03:00, 15:00–21:00, 23:00–24:00 Jul 20 00:00–03:00 Jul 21 16:00–17:00, 23:00–24:00 Jul 22 00:00–02:00 Jul 23 06:00–12:00 Jul 24 05:00–08:00, 20:00–24:00 Jul 25 01:00–02:00, 19:00–23:00 Jul 26 01:00–05:00, 20:00–24:00