Most often in May, 27 days.
Highest follower count seen that year: 16,551.
January
Jan 6 19:00–24:00 Jan 7 00:00–04:00, 19:00–24:00 Jan 8 00:00–03:00, 19:00–24:00 Jan 9 00:00–03:00, 19:00–24:00 Jan 10 00:00–03:00, 19:00–24:00 Jan 11 00:00–04:00, 17:00–23:00 Jan 14 19:00–24:00 Jan 15 00:00–05:00, 19:00–24:00 Jan 16 00:00–03:00, 19:00–24:00 Jan 17 00:00–05:00, 20:00–24:00 Jan 18 00:00–05:00, 19:00–23:00 Jan 21 19:00–24:00 Jan 22 00:00–04:00, 22:00–24:00 Jan 23 00:00–02:00 Jan 28 21:00–24:00 Jan 29 00:00–03:00, 19:00–24:00 Jan 30 00:00–03:00, 19:00–24:00 Jan 31 00:00–03:00, 20:00–24:00
February
Feb 1 00:00–03:00, 18:00–23:00 Feb 4 00:00–03:00, 19:00–24:00 Feb 5 00:00–03:00, 19:00–24:00 Feb 6 00:00–03:00, 19:00–24:00 Feb 7 00:00–03:00, 20:00–24:00 Feb 8 00:00–03:00 Feb 11 19:00–24:00 Feb 12 00:00–03:00, 20:00–24:00 Feb 13 00:00–03:00, 19:00–23:00 Feb 14 00:00–04:00, 19:00–24:00 Feb 15 00:00–03:00, 17:00–23:00 Feb 17 19:00–24:00 Feb 18 00:00–04:00, 19:00–24:00 Feb 19 00:00–05:00, 19:00–24:00 Feb 20 00:00–03:00, 19:00–24:00 Feb 21 00:00–05:00, 19:00–21:00
March
Mar 4 19:00–24:00 Mar 5 00:00–02:00, 20:00–24:00 Mar 6 00:00–03:00, 20:00–24:00 Mar 7 00:00–03:00, 20:00–24:00 Mar 8 00:00–03:00, 18:00–24:00 Mar 10 19:00–24:00 Mar 11 00:00–03:00, 19:00–24:00 Mar 12 00:00–03:00, 19:00–24:00 Mar 13 00:00–01:00, 03:00–04:00, 23:00–24:00 Mar 14 00:00–07:00, 23:00–24:00 Mar 15 00:00–07:00 Mar 16 00:00–07:00 Mar 18 23:00–24:00 Mar 19 00:00–07:00, 23:00–24:00 Mar 20 00:00–07:00, 23:00–24:00 Mar 21 00:00–07:00, 23:00–24:00 Mar 22 00:00–07:00, 23:00–24:00 Mar 23 00:00–05:00 Mar 24 23:00–24:00 Mar 25 00:00–07:00, 23:00–24:00 Mar 26 00:00–07:00, 23:00–24:00 Mar 27 00:00–07:00 Mar 28 23:00–24:00 Mar 29 00:00–07:00, 23:00–24:00 Mar 30 00:00–05:00 Mar 31 23:00–24:00
April
Apr 1 00:00–07:00, 23:00–24:00 Apr 2 00:00–07:00, 23:00–24:00 Apr 3 00:00–07:00, 23:00–24:00 Apr 4 00:00–07:00, 23:00–24:00 Apr 5 00:00–07:00 Apr 6 00:00–05:00 Apr 7 23:00–24:00 Apr 8 00:00–07:00, 23:00–24:00 Apr 9 00:00–07:00 Apr 10 23:00–24:00 Apr 11 00:00–07:00, 23:00–24:00 Apr 12 00:00–07:00, 23:00–24:00 Apr 13 00:00–05:00 Apr 14 01:00–05:00, 23:00–24:00 Apr 15 00:00–07:00, 23:00–24:00 Apr 16 00:00–07:00, 23:00–24:00 Apr 17 00:00–07:00 Apr 23 00:00–07:00, 23:00–24:00 Apr 24 00:00–07:00, 23:00–24:00 Apr 25 00:00–07:00, 23:00–24:00 Apr 26 00:00–07:00, 23:00–24:00 Apr 27 00:00–05:00 Apr 28 23:00–24:00 Apr 29 00:00–07:00 Apr 30 00:00–04:00, 23:00–24:00
May
May 1 00:00–07:00 May 2 23:00–24:00 May 3 00:00–07:00 May 4 04:00–05:00 May 5 23:00–24:00 May 6 00:00–07:00 May 7 02:00–07:00, 23:00–24:00 May 8 00:00–07:00 May 9 00:00–07:00 May 11 00:00–01:00 May 13 03:00–07:00, 23:00–24:00 May 14 00:00–07:00, 23:00–24:00 May 15 00:00–07:00 May 16 00:00–07:00, 23:00–24:00 May 17 00:00–07:00, 23:00–24:00 May 18 00:00–06:00 May 20 00:00–07:00 May 21 23:00–24:00 May 22 00:00–07:00, 23:00–24:00 May 23 02:00–07:00 May 24 00:00–07:00, 17:00–23:00 May 26 23:00–24:00 May 27 00:00–07:00, 23:00–24:00 May 28 00:00–06:00 May 29 23:00–24:00 May 30 00:00–07:00, 23:00–24:00 May 31 00:00–07:00, 15:00–21:00
June
Jun 3 23:00–24:00 Jun 4 00:00–07:00, 23:00–24:00 Jun 5 00:00–07:00, 23:00–24:00 Jun 6 00:00–07:00 Jun 7 00:00–07:00, 23:00–24:00 Jun 8 00:00–03:00 Jun 9 23:00–24:00 Jun 10 00:00–07:00, 23:00–24:00 Jun 11 00:00–07:00, 23:00–24:00 Jun 12 00:00–07:00, 23:00–24:00 Jun 13 00:00–07:00, 23:00–24:00 Jun 14 00:00–07:00, 23:00–24:00 Jun 15 00:00–05:00 Jun 16 23:00–24:00 Jun 17 00:00–07:00, 23:00–24:00 Jun 18 00:00–07:00 Jun 19 01:00–07:00, 23:00–24:00 Jun 20 00:00–07:00 Jun 21 23:00–24:00 Jun 22 00:00–06:00 Jun 24 23:00–24:00 Jun 25 00:00–06:00 Jun 26 00:00–07:00 Jun 27 00:00–07:00, 23:00–24:00 Jun 28 00:00–07:00, 23:00–24:00 Jun 29 00:00–05:00
July
Jul 2 23:00–24:00 Jul 3 00:00–07:00, 23:00–24:00 Jul 4 00:00–04:00, 23:00–24:00 Jul 5 00:00–07:00 Jul 6 00:00–05:00 Jul 8 00:00–07:00, 23:00–24:00 Jul 9 00:00–07:00, 23:00–24:00 Jul 10 00:00–02:00, 23:00–24:00 Jul 11 00:00–07:00, 23:00–24:00 Jul 12 00:00–07:00 Jul 13 00:00–05:00 Jul 15 00:00–07:00 Jul 17 02:00–07:00 Jul 18 01:00–07:00 Jul 19 00:00–05:00, 23:00–24:00 Jul 20 00:00–05:00 Jul 21 23:00–24:00 Jul 22 00:00–02:00 Jul 24 00:00–07:00 Jul 29 00:00–07:00, 23:00–24:00 Jul 30 00:00–07:00 Jul 31 01:00–07:00
August
Aug 1 00:00–07:00 Aug 2 00:00–07:00 Aug 5 06:00–08:00, 23:00–24:00 Aug 6 00:00–07:00 Aug 7 00:00–07:00 Aug 9 00:00–06:00 Aug 10 00:00–05:00 Aug 11 23:00–24:00 Aug 12 00:00–04:00 Aug 13 00:00–07:00, 23:00–24:00 Aug 14 00:00–07:00 Aug 15 00:00–07:00 Aug 16 00:00–06:00 Aug 20 00:00–07:00
September
Sep 10 02:00–10:00 Sep 11 02:00–09:00 Sep 12 02:00–08:00 Sep 13 02:00–09:00 Sep 16 02:00–08:00 Sep 17 02:00–08:00 Sep 19 02:00–08:00 Sep 20 02:00–06:00 Sep 21 02:00–08:00 Sep 22 02:00–06:00 Sep 25 02:00–09:00 Sep 27 02:00–09:00 Sep 29 02:00–10:00
October
Oct 2 02:00–06:00 Oct 5 03:00–08:00 Oct 6 02:00–06:00 Oct 9 02:00–08:00 Oct 11 02:00–05:00 Oct 12 02:00–08:00 Oct 15 02:00–07:00 Oct 16 03:00–04:00 Oct 17 02:00–07:00 Oct 19 02:00–08:00 Oct 20 02:00–05:00 Oct 21 02:00–06:00 Oct 23 02:00–08:00 Oct 25 02:00–06:00
November
Nov 9 02:00–07:00 Nov 11 02:00–07:00 Nov 16 02:00–07:00 Nov 20 02:00–05:00 Nov 21 02:00–03:00 Nov 26 02:00–08:00 Nov 27 03:00–07:00 Nov 30 02:00–06:00
December
Dec 2 02:00–06:00 Dec 6 03:00–05:00 Dec 9 02:00–08:00 Dec 10 03:00–06:00 Dec 12 02:00–07:00 Dec 17 02:00–08:00 Dec 18 02:00–07:00