Most often in May, 30 days.
Highest follower count seen that year: 7,434.
January
Jan 1 23:00–24:00 Jan 2 00:00–05:00, 23:00–24:00 Jan 3 00:00–07:00 Jan 7 05:00–07:00, 23:00–24:00 Jan 8 00:00–06:00, 15:00–17:00 Jan 9 01:00–07:00, 15:00–19:00 Jan 10 00:00–07:00, 15:00–18:00, 23:00–24:00 Jan 11 00:00–06:00 Jan 12 00:00–05:00 Jan 15 05:00–07:00, 23:00–24:00 Jan 16 00:00–05:00, 23:00–24:00 Jan 17 00:00–07:00, 15:00–18:00, 23:00–24:00 Jan 18 00:00–03:00 Jan 19 00:00–07:00, 23:00–24:00 Jan 20 00:00–07:00 Jan 21 00:00–07:00, 23:00–24:00 Jan 22 00:00–07:00 Jan 23 00:00–07:00, 23:00–24:00 Jan 24 00:00–07:00, 23:00–24:00 Jan 25 01:00–05:00 Jan 26 00:00–05:00, 23:00–24:00 Jan 27 00:00–07:00, 23:00–24:00 Jan 28 00:00–06:00, 23:00–24:00 Jan 29 00:00–05:00 Jan 30 01:00–02:00, 07:00–09:00 Jan 31 00:00–05:00
February
Feb 1 00:00–06:00, 23:00–24:00 Feb 2 00:00–04:00 Feb 3 23:00–24:00 Feb 4 00:00–06:00, 23:00–24:00 Feb 5 00:00–04:00, 23:00–24:00 Feb 6 00:00–06:00 Feb 7 23:00–24:00 Feb 8 00:00–05:00, 23:00–24:00 Feb 9 00:00–05:00 Feb 10 01:00–06:00, 23:00–24:00 Feb 11 00:00–03:00 Feb 12 23:00–24:00 Feb 13 00:00–04:00, 07:00–09:00 Feb 14 23:00–24:00 Feb 15 00:00–05:00 Feb 18 23:00–24:00 Feb 19 00:00–07:00 Feb 20 00:00–06:00 Feb 21 00:00–06:00 Feb 22 02:00–05:00 Feb 23 00:00–05:00 Feb 25 03:00–07:00 Feb 27 00:00–06:00 Feb 28 00:00–06:00
March
Mar 2 07:00–08:00 Mar 5 00:00–05:00 Mar 9 00:00–03:00 Mar 10 23:00–24:00 Mar 11 00:00–06:00, 23:00–24:00 Mar 12 00:00–05:00 Mar 14 23:00–24:00 Mar 15 00:00–05:00, 23:00–24:00 Mar 16 00:00–01:00, 23:00–24:00 Mar 17 00:00–06:00 Mar 18 00:00–05:00, 23:00–24:00 Mar 19 00:00–03:00 Mar 20 23:00–24:00 Mar 21 00:00–06:00, 23:00–24:00 Mar 22 00:00–05:00 Mar 24 23:00–24:00 Mar 25 00:00–06:00 Mar 29 23:00–24:00 Mar 30 00:00–04:00, 23:00–24:00 Mar 31 00:00–03:00, 23:00–24:00
April
Apr 1 00:00–01:00 Apr 9 01:00–07:00 Apr 10 00:00–06:00 Apr 11 04:00–07:00 Apr 12 04:00–06:00 Apr 13 00:00–06:00 Apr 14 00:00–04:00 Apr 15 01:00–05:00 Apr 17 04:00–05:00 Apr 20 00:00–03:00, 23:00–24:00 Apr 21 00:00–04:00 Apr 23 02:00–06:00, 17:00–20:00 Apr 24 16:00–19:00 Apr 25 00:00–03:00, 15:00–20:00 Apr 26 01:00–05:00, 15:00–19:00 Apr 27 16:00–20:00 Apr 28 01:00–06:00, 16:00–20:00 Apr 29 02:00–04:00, 16:00–20:00 Apr 30 02:00–05:00, 16:00–20:00
May
May 1 01:00–04:00, 16:00–20:00 May 2 01:00–05:00 May 3 02:00–05:00, 19:00–20:00 May 4 00:00–02:00, 16:00–20:00 May 5 01:00–05:00 May 6 01:00–05:00, 16:00–19:00 May 7 00:00–05:00, 13:00–15:00 May 8 02:00–03:00, 17:00–20:00 May 9 15:00–19:00 May 11 15:00–19:00 May 12 01:00–04:00, 16:00–19:00 May 13 17:00–18:00 May 14 00:00–01:00, 19:00–20:00 May 15 01:00–03:00, 17:00–20:00 May 16 01:00–02:00, 04:00–05:00, 17:00–19:00 May 17 18:00–19:00 May 18 00:00–06:00, 23:00–24:00 May 19 00:00–04:00, 16:00–19:00 May 20 19:00–20:00 May 21 16:00–19:00 May 22 01:00–04:00, 18:00–20:00 May 23 00:00–04:00, 16:00–18:00 May 24 01:00–04:00, 16:00–19:00 May 25 00:00–02:00, 16:00–20:00 May 26 01:00–04:00, 16:00–19:00 May 27 01:00–04:00 May 28 01:00–02:00 May 29 16:00–20:00 May 30 02:00–05:00 May 31 00:00–04:00
June
Jun 1 00:00–06:00, 15:00–18:00 Jun 2 00:00–05:00, 16:00–19:00 Jun 3 00:00–06:00 Jun 4 17:00–21:00 Jun 5 02:00–05:00, 18:00–19:00 Jun 6 01:00–05:00, 17:00–19:00 Jun 7 18:00–20:00 Jun 8 02:00–05:00 Jun 9 00:00–03:00 Jun 12 01:00–04:00 Jun 13 02:00–06:00, 18:00–19:00 Jun 16 00:00–07:00 Jun 17 01:00–02:00, 04:00–09:00 Jun 18 02:00–06:00 Jun 19 01:00–06:00 Jun 20 01:00–07:00 Jun 21 00:00–08:00 Jun 22 02:00–07:00 Jun 24 00:00–05:00 Jun 25 01:00–07:00, 16:00–18:00 Jun 26 00:00–04:00, 17:00–19:00 Jun 27 03:00–04:00, 16:00–18:00 Jun 28 04:00–07:00 Jun 29 00:00–07:00 Jun 30 02:00–07:00, 15:00–17:00
July
Jul 1 00:00–05:00, 18:00–19:00 Jul 2 04:00–06:00, 17:00–20:00 Jul 3 00:00–07:00, 14:00–19:00 Jul 4 03:00–07:00, 16:00–19:00 Jul 5 02:00–08:00, 17:00–20:00 Jul 6 00:00–02:00 Jul 7 00:00–06:00, 18:00–19:00 Jul 9 00:00–06:00 Jul 10 02:00–06:00, 17:00–19:00 Jul 11 01:00–06:00, 17:00–19:00 Jul 12 01:00–03:00 Jul 13 00:00–05:00 Jul 14 01:00–06:00 Jul 15 01:00–05:00 Jul 16 02:00–06:00 Jul 17 00:00–07:00 Jul 18 02:00–09:00 Jul 19 01:00–06:00 Jul 20 00:00–06:00 Jul 21 03:00–04:00 Jul 22 00:00–05:00 Jul 23 01:00–07:00 Jul 25 03:00–05:00 Jul 26 00:00–06:00, 23:00–24:00 Jul 27 00:00–02:00, 05:00–07:00