Most often in January, 31 days.
Highest follower count seen that year: 21,205.
January
Jan 1 00:00–02:00, 07:00–09:00, 14:00–16:00, 20:00–21:00 Jan 2 01:00–03:00, 14:00–16:00, 20:00–21:00 Jan 3 01:00–02:00, 14:00–16:00, 21:00–22:00 Jan 4 19:00–21:00, 23:00–24:00 Jan 5 00:00–01:00, 11:00–12:00, 22:00–23:00 Jan 6 11:00–12:00 Jan 7 00:00–01:00, 23:00–24:00 Jan 8 00:00–01:00 Jan 9 00:00–01:00, 09:00–11:00, 21:00–23:00 Jan 10 12:00–15:00, 18:00–19:00 Jan 11 02:00–03:00, 10:00–11:00, 20:00–21:00 Jan 12 01:00–02:00 Jan 13 00:00–02:00, 11:00–12:00, 18:00–20:00, 23:00–24:00 Jan 14 01:00–02:00, 11:00–12:00 Jan 15 00:00–01:00, 23:00–24:00 Jan 16 00:00–01:00, 10:00–11:00, 18:00–20:00, 23:00–24:00 Jan 17 00:00–01:00, 12:00–14:00, 19:00–21:00 Jan 18 18:00–19:00 Jan 19 00:00–01:00, 11:00–12:00, 22:00–23:00 Jan 20 06:00–07:00, 11:00–12:00, 23:00–24:00 Jan 21 23:00–24:00 Jan 22 20:00–22:00 Jan 23 02:00–04:00, 12:00–14:00 Jan 24 00:00–01:00, 17:00–18:00, 20:00–21:00 Jan 25 01:00–02:00, 08:00–09:00, 14:00–15:00 Jan 26 01:00–02:00, 14:00–15:00, 19:00–20:00 Jan 27 00:00–01:00, 10:00–12:00, 23:00–24:00 Jan 28 01:00–02:00, 11:00–12:00 Jan 29 01:00–03:00, 21:00–22:00 Jan 30 17:00–19:00, 23:00–24:00 Jan 31 12:00–13:00, 17:00–18:00
February
Feb 1 13:00–14:00, 17:00–19:00, 23:00–24:00 Feb 2 12:00–13:00, 19:00–20:00 Feb 4 01:00–02:00, 11:00–12:00, 23:00–24:00 Feb 5 21:00–22:00 Feb 6 05:00–06:00, 14:00–15:00, 17:00–18:00 Feb 7 01:00–03:00, 10:00–12:00, 16:00–17:00 Feb 8 03:00–04:00, 21:00–22:00 Feb 9 11:00–12:00, 22:00–23:00 Feb 10 03:00–04:00 Feb 11 00:00–01:00 Feb 13 00:00–01:00, 12:00–13:00, 19:00–20:00 Feb 14 01:00–02:00, 14:00–15:00, 22:00–23:00 Feb 15 18:00–19:00 Feb 16 01:00–02:00, 11:00–12:00, 22:00–23:00 Feb 17 02:00–03:00, 12:00–13:00, 23:00–24:00 Feb 18 09:00–11:00 Feb 19 00:00–01:00, 20:00–21:00 Feb 20 06:00–08:00, 16:00–18:00 Feb 21 00:00–02:00, 14:00–15:00 Feb 22 23:00–24:00 Feb 23 05:00–06:00, 12:00–13:00, 23:00–24:00 Feb 24 11:00–12:00, 23:00–24:00 Feb 25 00:00–01:00, 11:00–12:00 Feb 26 01:00–02:00, 21:00–22:00 Feb 27 06:00–07:00, 13:00–14:00, 20:00–21:00 Feb 28 05:00–06:00, 15:00–16:00
March
Mar 1 01:00–02:00, 09:00–10:00, 18:00–19:00 Mar 2 00:00–01:00, 10:00–11:00, 22:00–23:00 Mar 3 09:00–10:00, 22:00–23:00 Mar 4 03:00–04:00, 11:00–12:00 Mar 6 01:00–02:00, 13:00–14:00, 19:00–20:00 Mar 7 14:00–15:00 Mar 8 09:00–10:00, 19:00–21:00 Mar 9 21:00–22:00 Mar 10 10:00–11:00, 23:00–24:00 Mar 11 23:00–24:00 Mar 12 22:00–23:00 Mar 13 10:00–12:00, 22:00–23:00 Mar 14 10:00–12:00, 21:00–24:00 Mar 15 18:00–19:00 Mar 16 21:00–23:00 Mar 18 00:00–01:00, 22:00–23:00 Mar 21 17:00–19:00 Mar 22 00:00–03:00, 20:00–22:00 Mar 23 22:00–24:00 Mar 24 22:00–23:00 Mar 25 10:00–11:00 Mar 26 00:00–02:00, 21:00–22:00 Mar 27 05:00–07:00, 15:00–17:00, 20:00–21:00 Mar 28 09:00–10:00, 19:00–20:00 Mar 29 01:00–03:00, 19:00–20:00 Mar 30 21:00–23:00 Mar 31 09:00–10:00, 21:00–22:00
April
Apr 2 00:00–01:00, 23:00–24:00 Apr 3 00:00–01:00, 05:00–06:00 Apr 4 09:00–10:00, 18:00–19:00 Apr 5 03:00–05:00, 17:00–18:00, 22:00–23:00 Apr 6 21:00–24:00 Apr 7 00:00–01:00, 22:00–23:00 Apr 8 10:00–11:00, 13:00–15:00 Apr 9 23:00–24:00 Apr 10 05:00–07:00, 13:00–15:00, 18:00–19:00 Apr 11 11:00–12:00, 18:00–20:00, 23:00–24:00 Apr 12 20:00–21:00 Apr 13 03:00–04:00, 20:00–21:00 Apr 14 09:00–11:00, 22:00–23:00 Apr 15 05:00–06:00, 21:00–23:00 Apr 16 22:00–23:00 Apr 17 01:00–03:00, 13:00–15:00, 22:00–23:00 Apr 18 07:00–08:00, 21:00–23:00 Apr 19 18:00–20:00 Apr 20 02:00–03:00, 23:00–24:00 Apr 21 01:00–02:00, 10:00–11:00, 23:00–24:00 Apr 22 11:00–12:00, 23:00–24:00 Apr 23 23:00–24:00 Apr 24 05:00–07:00, 12:00–13:00, 20:00–21:00 Apr 25 04:00–05:00, 15:00–17:00, 22:00–23:00 Apr 26 18:00–19:00 Apr 28 00:00–02:00, 10:00–12:00, 22:00–23:00 Apr 29 01:00–02:00, 10:00–11:00, 22:00–23:00 Apr 30 22:00–23:00
May
May 1 05:00–07:00, 12:00–13:00, 21:00–22:00 May 2 11:00–12:00, 19:00–20:00 May 3 22:00–23:00 May 4 11:00–12:00, 18:00–19:00 May 5 00:00–01:00, 10:00–11:00, 21:00–22:00 May 6 10:00–11:00 May 7 00:00–01:00, 21:00–22:00 May 8 17:00–18:00, 23:00–24:00 May 9 10:00–12:00, 18:00–19:00, 23:00–24:00 May 10 22:00–23:00 May 11 01:00–02:00, 13:00–15:00, 23:00–24:00 May 13 10:00–11:00, 23:00–24:00 May 14 00:00–01:00 May 15 04:00–05:00, 12:00–14:00, 19:00–20:00 May 16 12:00–14:00 May 17 22:00–23:00 May 19 00:00–01:00, 10:00–11:00, 22:00–23:00 May 20 01:00–02:00, 10:00–11:00 May 22 00:00–01:00, 17:00–18:00, 23:00–24:00 May 23 12:00–13:00, 17:00–18:00, 22:00–23:00 May 24 17:00–18:00, 22:00–23:00 May 25 04:00–05:00, 22:00–23:00 May 26 02:00–03:00, 22:00–23:00 May 27 10:00–11:00 May 28 00:00–01:00, 23:00–24:00 May 29 14:00–15:00, 22:00–23:00 May 30 07:00–08:00, 12:00–13:00, 19:00–20:00 May 31 00:00–01:00, 21:00–22:00
June
Jun 1 00:00–01:00, 22:00–24:00 Jun 2 02:00–03:00, 20:00–24:00 Jun 3 10:00–11:00 Jun 4 00:00–01:00, 22:00–24:00 Jun 5 08:00–09:00, 14:00–15:00, 18:00–19:00 Jun 6 01:00–02:00, 11:00–12:00, 19:00–20:00 Jun 7 19:00–20:00, 22:00–23:00 Jun 8 21:00–22:00 Jun 9 01:00–02:00, 10:00–11:00 Jun 10 01:00–02:00, 04:00–05:00, 22:00–24:00 Jun 11 00:00–01:00, 22:00–24:00 Jun 12 15:00–17:00 Jun 13 00:00–01:00, 09:00–11:00, 15:00–17:00 Jun 15 20:00–21:00 Jun 16 03:00–04:00, 11:00–12:00, 22:00–23:00 Jun 17 02:00–03:00, 11:00–12:00 Jun 18 22:00–23:00 Jun 19 13:00–14:00, 20:00–22:00 Jun 20 01:00–02:00, 05:00–07:00, 15:00–16:00, 22:00–23:00 Jun 21 16:00–17:00, 23:00–24:00 Jun 22 23:00–24:00 Jun 23 10:00–11:00, 21:00–22:00 Jun 24 00:00–01:00, 10:00–11:00, 22:00–23:00 Jun 25 23:00–24:00 Jun 26 03:00–04:00, 13:00–14:00, 18:00–19:00 Jun 27 17:00–18:00, 22:00–23:00 Jun 28 18:00–19:00, 22:00–23:00 Jun 29 20:00–21:00 Jun 30 04:00–06:00, 21:00–24:00
July
Jul 1 10:00–11:00, 22:00–24:00 Jul 2 21:00–23:00 Jul 3 12:00–13:00, 19:00–21:00 Jul 4 01:00–02:00, 13:00–14:00, 18:00–19:00, 22:00–23:00 Jul 5 00:00–01:00, 20:00–21:00 Jul 6 03:00–04:00, 18:00–19:00, 23:00–24:00 Jul 7 10:00–11:00, 20:00–22:00 Jul 8 10:00–11:00, 23:00–24:00 Jul 9 22:00–23:00 Jul 10 08:00–09:00, 16:00–17:00 Jul 11 01:00–02:00, 12:00–13:00, 16:00–17:00, 23:00–24:00 Jul 12 19:00–20:00, 22:00–23:00 Jul 13 23:00–24:00 Jul 14 21:00–22:00 Jul 15 02:00–03:00, 23:00–24:00 Jul 16 01:00–02:00, 22:00–23:00 Jul 17 11:00–12:00, 19:00–21:00 Jul 18 11:00–13:00, 19:00–21:00 Jul 19 01:00–02:00, 18:00–19:00, 23:00–24:00 Jul 22 01:00–02:00, 23:00–24:00 Jul 23 00:00–01:00, 23:00–24:00 Jul 24 01:00–02:00, 06:00–07:00, 17:00–18:00 Jul 25 00:00–01:00, 11:00–12:00, 14:00–15:00, 22:00–23:00 Jul 26 17:00–19:00, 23:00–24:00 Jul 27 00:00–01:00