Most often in January, 31 days.
Highest follower count seen that year: 3,148.
January
Jan 1 04:00–07:00, 16:00–19:00 Jan 2 04:00–05:00, 15:00–19:00 Jan 3 03:00–06:00, 15:00–18:00 Jan 4 02:00–03:00, 05:00–08:00, 12:00–17:00 Jan 5 10:00–11:00, 13:00–14:00, 16:00–18:00 Jan 6 09:00–11:00, 13:00–17:00 Jan 7 03:00–09:00, 15:00–17:00, 23:00–24:00 Jan 8 04:00–06:00, 14:00–18:00 Jan 9 04:00–07:00, 15:00–18:00 Jan 10 04:00–10:00, 13:00–17:00 Jan 11 07:00–10:00, 14:00–18:00 Jan 12 07:00–11:00, 15:00–17:00 Jan 13 04:00–06:00, 09:00–11:00, 13:00–14:00, 17:00–19:00 Jan 14 05:00–10:00, 12:00–14:00, 16:00–18:00 Jan 15 15:00–17:00 Jan 16 04:00–06:00 Jan 17 04:00–05:00, 07:00–10:00, 14:00–18:00 Jan 18 04:00–05:00, 17:00–19:00 Jan 19 04:00–07:00, 14:00–18:00 Jan 20 09:00–14:00, 17:00–19:00 Jan 21 09:00–12:00, 15:00–17:00 Jan 22 13:00–14:00, 17:00–19:00 Jan 23 02:00–08:00, 16:00–19:00 Jan 24 05:00–07:00, 10:00–11:00, 15:00–18:00 Jan 25 03:00–07:00, 15:00–18:00 Jan 26 07:00–10:00, 16:00–17:00 Jan 27 01:00–02:00, 16:00–18:00 Jan 28 13:00–15:00, 17:00–18:00 Jan 29 05:00–06:00, 15:00–17:00 Jan 30 03:00–08:00, 15:00–17:00 Jan 31 04:00–07:00, 10:00–13:00, 15:00–17:00
February
Feb 1 05:00–08:00, 14:00–16:00 Feb 2 15:00–16:00 Feb 3 14:00–16:00 Feb 4 13:00–17:00 Feb 5 17:00–18:00 Feb 7 14:00–17:00 Feb 8 05:00–08:00, 16:00–18:00 Feb 9 05:00–08:00, 10:00–13:00, 16:00–18:00 Feb 10 16:00–19:00 Feb 11 04:00–06:00, 14:00–16:00 Feb 12 15:00–17:00 Feb 13 03:00–06:00 Feb 14 04:00–06:00 Feb 15 04:00–06:00, 16:00–18:00
March
Mar 4 16:00–18:00 Mar 5 04:00–05:00, 17:00–19:00 Mar 6 14:00–19:00 Mar 7 17:00–19:00 Mar 8 08:00–11:00, 17:00–19:00 Mar 9 17:00–18:00 Mar 10 18:00–19:00 Mar 11 07:00–08:00, 10:00–14:00, 18:00–19:00 Mar 12 03:00–06:00 Mar 14 16:00–18:00 Mar 15 08:00–10:00, 16:00–18:00 Mar 16 17:00–20:00 Mar 17 08:00–09:00 Mar 18 16:00–18:00 Mar 19 08:00–13:00 Mar 21 15:00–17:00 Mar 22 16:00–19:00 Mar 24 17:00–18:00 Mar 25 18:00–19:00 Mar 26 12:00–14:00 Mar 28 04:00–05:00, 13:00–16:00, 18:00–20:00 Mar 29 16:00–20:00 Mar 30 11:00–14:00, 17:00–18:00 Mar 31 09:00–13:00, 16:00–19:00
April
Apr 1 02:00–03:00, 05:00–08:00, 11:00–14:00, 17:00–20:00 Apr 2 14:00–17:00 Apr 3 03:00–05:00, 10:00–17:00 Apr 4 06:00–08:00, 16:00–19:00 Apr 5 06:00–10:00, 15:00–19:00 Apr 6 06:00–07:00, 09:00–11:00, 16:00–19:00 Apr 7 11:00–17:00 Apr 8 07:00–14:00, 16:00–18:00 Apr 9 06:00–11:00, 16:00–17:00 Apr 10 04:00–06:00, 09:00–13:00, 16:00–17:00 Apr 11 16:00–18:00 Apr 12 02:00–03:00, 06:00–07:00, 10:00–13:00, 16:00–17:00 Apr 13 11:00–13:00, 16:00–18:00 Apr 14 03:00–04:00, 09:00–11:00, 14:00–17:00 Apr 15 05:00–07:00, 12:00–13:00 Apr 16 02:00–06:00, 17:00–19:00 Apr 17 02:00–06:00, 16:00–20:00 Apr 18 05:00–07:00, 14:00–19:00 Apr 19 05:00–07:00, 17:00–20:00 Apr 20 13:00–18:00 Apr 21 08:00–12:00 Apr 22 00:00–07:00, 16:00–19:00 Apr 23 03:00–06:00, 17:00–20:00 Apr 24 01:00–05:00, 13:00–19:00 Apr 25 05:00–06:00, 10:00–11:00, 16:00–18:00 Apr 26 02:00–05:00, 07:00–09:00, 16:00–18:00 Apr 27 01:00–02:00, 04:00–07:00, 16:00–19:00 Apr 28 03:00–09:00, 17:00–19:00 Apr 29 03:00–06:00, 16:00–18:00 Apr 30 03:00–07:00, 16:00–18:00
May
May 1 02:00–06:00, 16:00–19:00 May 2 04:00–06:00 May 3 07:00–09:00, 17:00–19:00 May 4 07:00–09:00, 17:00–18:00 May 5 03:00–05:00 May 12 16:00–18:00 May 13 03:00–05:00, 16:00–18:00 May 14 10:00–12:00 May 15 16:00–18:00 May 16 16:00–18:00 May 17 02:00–07:00 May 18 14:00–18:00 May 19 04:00–05:00, 16:00–19:00 May 20 16:00–18:00 May 21 10:00–11:00, 17:00–18:00 May 22 18:00–19:00 May 23 04:00–08:00, 11:00–14:00, 16:00–18:00 May 24 06:00–13:00, 16:00–18:00 May 25 03:00–05:00, 12:00–18:00 May 26 03:00–06:00, 16:00–19:00 May 27 02:00–08:00, 12:00–15:00, 17:00–19:00 May 28 13:00–15:00, 17:00–19:00 May 29 01:00–02:00, 15:00–18:00 May 30 03:00–05:00, 08:00–10:00, 15:00–17:00 May 31 03:00–07:00, 16:00–18:00
June
Jun 1 03:00–05:00, 17:00–18:00 Jun 2 02:00–04:00, 17:00–19:00 Jun 3 03:00–04:00, 08:00–10:00, 13:00–15:00 Jun 4 18:00–20:00 Jun 5 10:00–12:00, 15:00–17:00, 19:00–20:00 Jun 6 03:00–04:00 Jun 7 04:00–06:00, 09:00–11:00, 15:00–17:00 Jun 8 03:00–05:00, 16:00–19:00 Jun 9 13:00–20:00 Jun 10 12:00–16:00, 18:00–19:00 Jun 11 02:00–03:00 Jun 12 16:00–19:00 Jun 13 13:00–18:00 Jun 15 09:00–11:00, 16:00–19:00 Jun 16 03:00–05:00, 08:00–12:00, 17:00–18:00 Jun 17 09:00–10:00, 16:00–17:00 Jun 18 04:00–05:00, 08:00–10:00, 15:00–18:00 Jun 19 16:00–17:00 Jun 20 10:00–11:00, 16:00–19:00 Jun 21 05:00–07:00, 15:00–18:00 Jun 22 03:00–04:00, 15:00–18:00 Jun 23 11:00–12:00, 17:00–19:00 Jun 24 02:00–05:00, 08:00–09:00 Jun 25 09:00–10:00, 17:00–18:00 Jun 26 17:00–19:00 Jun 28 04:00–08:00 Jun 29 02:00–05:00, 17:00–19:00 Jun 30 01:00–02:00, 06:00–07:00, 10:00–12:00, 16:00–17:00
July
Jul 1 02:00–03:00, 15:00–18:00 Jul 2 05:00–10:00, 16:00–19:00 Jul 3 04:00–06:00, 16:00–19:00 Jul 4 07:00–09:00, 16:00–17:00 Jul 5 18:00–19:00 Jul 6 03:00–06:00 Jul 7 09:00–12:00 Jul 8 04:00–05:00, 09:00–11:00, 16:00–18:00 Jul 9 03:00–04:00, 16:00–17:00 Jul 10 02:00–03:00, 07:00–08:00, 17:00–20:00 Jul 11 09:00–11:00, 16:00–18:00 Jul 12 05:00–09:00, 16:00–18:00 Jul 13 16:00–18:00 Jul 14 05:00–06:00, 10:00–12:00 Jul 15 05:00–06:00, 16:00–18:00 Jul 16 03:00–06:00, 17:00–18:00 Jul 17 08:00–09:00, 18:00–20:00 Jul 18 07:00–08:00 Jul 19 06:00–08:00, 15:00–19:00 Jul 20 10:00–13:00, 19:00–22:00 Jul 22 19:00–20:00 Jul 23 04:00–05:00, 12:00–17:00 Jul 24 05:00–06:00, 16:00–19:00 Jul 25 04:00–05:00, 17:00–18:00 Jul 26 17:00–18:00