Most often in April, 28 days.
Highest follower count seen that year: 84,930.
January
Jan 6 08:00–16:00 Jan 7 07:00–10:00, 13:00–16:00 Jan 8 08:00–10:00, 13:00–16:00 Jan 9 10:00–16:00 Jan 10 08:00–10:00 Jan 11 13:00–16:00 Jan 12 10:00–16:00 Jan 13 03:00–06:00, 13:00–21:00 Jan 14 12:00–15:00 Jan 15 13:00–16:00 Jan 16 13:00–21:00 Jan 17 12:00–15:00 Jan 18 12:00–20:00 Jan 19 13:00–16:00 Jan 20 04:00–07:00, 13:00–16:00 Jan 21 12:00–16:00 Jan 22 05:00–08:00, 13:00–15:00 Jan 23 05:00–08:00, 21:00–23:00 Jan 26 13:00–15:00, 18:00–20:00 Jan 27 13:00–16:00 Jan 28 00:00–04:00, 13:00–16:00 Jan 29 02:00–07:00, 13:00–16:00
February
Feb 1 13:00–16:00 Feb 2 01:00–05:00, 13:00–16:00 Feb 3 03:00–07:00, 13:00–16:00 Feb 4 12:00–15:00, 17:00–20:00 Feb 5 01:00–05:00, 13:00–16:00 Feb 6 04:00–07:00, 21:00–24:00 Feb 7 00:00–01:00 Feb 8 12:00–16:00 Feb 9 13:00–16:00, 21:00–24:00 Feb 10 00:00–02:00, 12:00–15:00, 20:00–24:00 Feb 11 13:00–16:00, 20:00–24:00 Feb 12 00:00–01:00, 13:00–16:00, 20:00–24:00 Feb 13 00:00–02:00, 21:00–24:00 Feb 14 00:00–03:00 Feb 15 13:00–16:00, 19:00–24:00 Feb 16 12:00–16:00 Feb 17 13:00–16:00, 19:00–24:00 Feb 18 13:00–16:00, 22:00–24:00 Feb 19 00:00–03:00, 13:00–16:00, 21:00–24:00 Feb 20 00:00–02:00 Feb 22 13:00–16:00 Feb 23 12:00–16:00 Feb 24 13:00–16:00, 22:00–24:00 Feb 25 00:00–01:00, 12:00–16:00, 21:00–24:00 Feb 26 00:00–02:00, 13:00–16:00
March
Mar 1 21:00–24:00 Mar 2 00:00–02:00, 12:00–16:00, 20:00–24:00 Mar 3 13:00–17:00 Mar 4 02:00–05:00, 13:00–16:00 Mar 5 13:00–16:00 Mar 6 20:00–23:00 Mar 9 12:00–16:00 Mar 10 13:00–16:00 Mar 13 13:00–16:00 Mar 17 12:00–16:00 Mar 18 13:00–16:00 Mar 20 12:00–16:00 Mar 21 07:00–10:00 Mar 22 12:00–16:00 Mar 23 07:00–09:00, 13:00–16:00, 20:00–24:00 Mar 24 12:00–16:00, 21:00–24:00 Mar 25 00:00–01:00, 13:00–16:00 Mar 26 13:00–15:00, 22:00–24:00 Mar 27 00:00–01:00, 21:00–24:00 Mar 28 00:00–01:00 Mar 29 20:00–23:00 Mar 30 13:00–16:00, 22:00–24:00 Mar 31 00:00–02:00, 21:00–24:00
April
Apr 1 00:00–01:00, 13:00–16:00 Apr 3 08:00–10:00 Apr 4 06:00–10:00 Apr 5 08:00–10:00, 12:00–15:00 Apr 6 13:00–16:00 Apr 7 08:00–10:00 Apr 8 09:00–16:00 Apr 9 09:00–16:00, 22:00–24:00 Apr 10 00:00–01:00, 08:00–11:00 Apr 11 12:00–15:00 Apr 12 08:00–12:00, 20:00–24:00 Apr 13 13:00–16:00 Apr 14 12:00–15:00, 21:00–24:00 Apr 15 00:00–01:00, 12:00–15:00 Apr 16 04:00–09:00 Apr 17 08:00–16:00 Apr 18 04:00–08:00 Apr 19 05:00–08:00, 13:00–16:00 Apr 20 12:00–16:00 Apr 21 03:00–07:00, 12:00–16:00 Apr 22 04:00–08:00, 12:00–16:00 Apr 23 04:00–08:00 Apr 25 02:00–05:00, 12:00–15:00 Apr 26 12:00–15:00 Apr 27 12:00–15:00 Apr 28 03:00–09:00 Apr 29 12:00–16:00 Apr 30 04:00–09:00, 12:00–15:00
May
May 1 02:00–07:00 May 3 03:00–07:00, 12:00–16:00 May 4 12:00–15:00 May 5 02:00–06:00, 12:00–15:00 May 7 03:00–04:00, 12:00–15:00 May 8 05:00–08:00, 21:00–24:00 May 9 01:00–02:00 May 10 03:00–07:00, 12:00–15:00 May 11 04:00–06:00, 12:00–15:00 May 12 03:00–07:00, 12:00–15:00 May 13 03:00–07:00, 12:00–15:00 May 14 03:00–07:00 May 15 04:00–07:00 May 17 12:00–16:00 May 18 02:00–07:00, 13:00–15:00 May 19 03:00–07:00, 12:00–15:00 May 20 03:00–07:00, 12:00–15:00 May 21 04:00–07:00, 12:00–14:00 May 22 02:00–07:00 May 25 03:00–07:00, 12:00–15:00 May 26 07:00–15:00 May 27 03:00–07:00 May 28 03:00–07:00 May 29 07:00–11:00
June
Jun 1 03:00–06:00, 18:00–22:00 Jun 2 12:00–15:00, 19:00–22:00 Jun 3 08:00–15:00 Jun 4 03:00–07:00 Jun 5 04:00–08:00 Jun 6 04:00–07:00, 12:00–15:00 Jun 8 03:00–06:00, 12:00–15:00 Jun 9 04:00–08:00, 12:00–15:00 Jun 10 03:00–07:00, 12:00–15:00 Jun 11 04:00–07:00 Jun 13 02:00–07:00, 12:00–15:00 Jun 16 03:00–07:00, 12:00–15:00 Jun 17 03:00–10:00 Jun 18 04:00–07:00, 12:00–15:00 Jun 20 02:00–07:00 Jun 21 12:00–15:00 Jun 22 12:00–19:00 Jun 23 04:00–06:00, 12:00–14:00 Jun 24 02:00–06:00 Jun 25 02:00–06:00 Jun 28 03:00–08:00, 12:00–15:00 Jun 29 11:00–15:00 Jun 30 12:00–15:00
July
Jul 1 03:00–05:00, 11:00–14:00 Jul 2 03:00–06:00 Jul 4 12:00–14:00 Jul 5 12:00–14:00 Jul 6 03:00–06:00 Jul 7 12:00–15:00 Jul 8 03:00–06:00, 12:00–14:00 Jul 9 12:00–13:00 Jul 10 03:00–07:00 Jul 11 03:00–07:00 Jul 12 04:00–08:00 Jul 13 03:00–07:00, 12:00–14:00 Jul 14 12:00–15:00 Jul 15 12:00–15:00 Jul 16 03:00–07:00, 12:00–15:00 Jul 17 04:00–07:00 Jul 19 03:00–07:00 Jul 20 12:00–15:00 Jul 21 03:00–07:00, 11:00–14:00 Jul 22 04:00–07:00 Jul 23 13:00–14:00 Jul 24 22:00–24:00 Jul 25 00:00–02:00 Jul 26 03:00–05:00, 12:00–15:00 Jul 27 05:00–07:00, 12:00–14:00