Most often in April, 27 days.
Highest follower count seen that year: 35,943.
March
Mar 24 01:00–04:00 Mar 25 01:00–07:00 Mar 26 01:00–07:00 Mar 27 01:00–07:00 Mar 28 01:00–06:00 Mar 29 02:00–07:00 Mar 30 01:00–05:00, 09:00–11:00 Mar 31 01:00–05:00, 10:00–11:00
April
Apr 2 01:00–07:00 Apr 3 01:00–06:00, 10:00–13:00 Apr 4 02:00–05:00, 08:00–13:00 Apr 5 02:00–06:00 Apr 6 02:00–07:00, 11:00–14:00 Apr 7 02:00–06:00 Apr 8 01:00–07:00, 12:00–13:00 Apr 9 01:00–06:00 Apr 10 02:00–06:00 Apr 11 01:00–12:00 Apr 12 01:00–06:00, 10:00–13:00 Apr 13 02:00–07:00 Apr 14 01:00–06:00, 11:00–13:00 Apr 16 01:00–06:00, 12:00–14:00 Apr 17 03:00–05:00, 09:00–12:00 Apr 18 02:00–05:00, 10:00–14:00 Apr 19 02:00–05:00, 12:00–13:00 Apr 20 09:00–13:00 Apr 21 02:00–07:00 Apr 23 02:00–04:00, 10:00–13:00 Apr 24 02:00–05:00, 10:00–13:00 Apr 25 02:00–05:00, 10:00–13:00 Apr 26 02:00–04:00, 10:00–13:00 Apr 27 02:00–05:00, 10:00–13:00 Apr 28 02:00–06:00, 10:00–13:00 Apr 29 03:00–05:00, 09:00–12:00 Apr 30 02:00–04:00, 08:00–12:00
May
May 1 03:00–04:00 May 2 03:00–06:00, 11:00–13:00 May 3 03:00–05:00, 11:00–13:00 May 4 09:00–12:00 May 6 07:00–12:00 May 7 03:00–05:00, 11:00–12:00 May 8 03:00–06:00, 10:00–12:00 May 9 02:00–06:00, 10:00–13:00 May 10 03:00–05:00, 09:00–12:00 May 11 03:00–05:00, 07:00–10:00 May 12 02:00–05:00, 11:00–13:00 May 13 02:00–05:00, 12:00–14:00 May 14 02:00–05:00, 08:00–11:00 May 15 02:00–04:00, 10:00–13:00 May 16 02:00–05:00, 10:00–12:00 May 17 02:00–05:00, 10:00–13:00 May 19 02:00–05:00, 09:00–12:00 May 21 02:00–03:00, 09:00–11:00 May 22 02:00–04:00, 09:00–13:00 May 23 02:00–05:00 May 24 02:00–04:00, 10:00–12:00 May 25 02:00–05:00, 10:00–12:00 May 26 01:00–04:00 May 28 03:00–05:00, 10:00–13:00 May 29 02:00–05:00, 10:00–13:00 May 30 02:00–05:00 May 31 02:00–05:00, 09:00–13:00
June
Jun 1 03:00–04:00, 08:00–13:00 Jun 2 02:00–06:00 Jun 4 02:00–06:00 Jun 5 02:00–05:00, 11:00–14:00 Jun 6 03:00–10:00 Jun 7 02:00–07:00 Jun 8 03:00–11:00 Jun 11 02:00–11:00 Jun 12 04:00–11:00 Jun 13 08:00–12:00 Jun 14 03:00–08:00 Jun 15 03:00–09:00 Jun 17 03:00–07:00 Jun 18 02:00–05:00, 09:00–13:00 Jun 19 02:00–05:00 Jun 20 03:00–08:00 Jun 21 02:00–08:00 Jun 22 03:00–09:00 Jun 24 03:00–12:00 Jun 26 03:00–08:00 Jun 27 05:00–11:00 Jun 28 03:00–07:00 Jun 29 01:00–07:00, 09:00–12:00
July
Jul 1 02:00–07:00, 10:00–12:00 Jul 2 03:00–11:00 Jul 3 03:00–09:00 Jul 4 02:00–10:00 Jul 5 03:00–09:00 Jul 6 03:00–10:00 Jul 8 03:00–10:00 Jul 9 03:00–10:00 Jul 10 03:00–04:00 Jul 11 03:00–09:00 Jul 12 03:00–05:00 Jul 13 03:00–10:00 Jul 15 05:00–12:00 Jul 16 03:00–09:00 Jul 18 04:00–11:00 Jul 19 03:00–08:00 Jul 22 03:00–10:00 Jul 23 03:00–10:00 Jul 24 03:00–09:00 Jul 25 03:00–07:00 Jul 26 03:00–09:00 Jul 27 07:00–10:00
August
Aug 1 02:00–09:00 Aug 2 03:00–10:00 Aug 4 04:00–11:00 Aug 5 06:00–09:00 Aug 6 03:00–07:00 Aug 7 05:00–11:00 Aug 8 03:00–11:00 Aug 9 04:00–11:00 Aug 10 03:00–10:00 Aug 12 03:00–11:00 Aug 13 03:00–09:00 Aug 15 07:00–12:00 Aug 16 07:00–12:00 Aug 17 03:00–09:00 Aug 20 03:00–13:00 Aug 21 03:00–10:00 Aug 22 05:00–12:00 Aug 23 04:00–08:00 Aug 24 04:00–13:00 Aug 26 03:00–10:00 Aug 27 03:00–11:00 Aug 29 04:00–12:00 Aug 30 04:00–07:00 Aug 31 04:00–10:00
September
Sep 1 06:00–08:00 Sep 3 05:00–11:00 Sep 5 05:00–09:00, 12:00–13:00 Sep 6 04:00–08:00 Sep 7 06:00–08:00 Sep 9 05:00–10:00 Sep 10 05:00–07:00 Sep 11 07:00–13:00 Sep 12 06:00–12:00 Sep 16 06:00–13:00 Sep 17 06:00–11:00 Sep 18 06:00–10:00 Sep 20 06:00–12:00 Sep 21 06:00–09:00 Sep 23 05:00–12:00 Sep 24 06:00–09:00 Sep 28 06:00–11:00
October
Oct 1 06:00–13:00 Oct 2 06:00–09:00 Oct 13 06:00–10:00 Oct 14 06:00–12:00 Oct 15 07:00–11:00 Oct 16 06:00–09:00 Oct 18 08:00–12:00 Oct 19 06:00–13:00 Oct 20 05:00–12:00 Oct 21 05:00–10:00 Oct 23 05:00–11:00 Oct 26 05:00–11:00 Oct 27 04:00–11:00 Oct 28 04:00–11:00 Oct 29 05:00–12:00 Oct 30 05:00–11:00
November
Nov 1 07:00–13:00 Nov 2 06:00–10:00 Nov 3 06:00–10:00 Nov 4 05:00–12:00 Nov 7 06:00–08:00 Nov 9 06:00–13:00 Nov 10 06:00–13:00 Nov 11 06:00–13:00 Nov 13 06:00–12:00 Nov 14 06:00–10:00 Nov 15 07:00–08:00 Nov 16 06:00–13:00 Nov 18 07:00–10:00 Nov 20 06:00–13:00 Nov 22 06:00–13:00 Nov 23 07:00–13:00 Nov 24 06:00–13:00 Nov 26 06:00–09:00 Nov 29 06:00–13:00 Nov 30 06:00–13:00
December
Dec 1 06:00–12:00 Dec 2 06:00–11:00 Dec 3 06:00–12:00 Dec 4 06:00–12:00 Dec 7 07:00–12:00 Dec 8 06:00–14:00 Dec 9 07:00–12:00 Dec 10 07:00–13:00 Dec 11 07:00–11:00 Dec 12 07:00–12:00 Dec 13 06:00–09:00 Dec 14 06:00–12:00 Dec 18 06:00–12:00 Dec 19 06:00–10:00 Dec 20 07:00–09:00 Dec 21 06:00–08:00 Dec 24 05:00–11:00 Dec 25 06:00–07:00 Dec 26 06:00–11:00 Dec 27 06:00–09:00 Dec 30 06:00–10:00 Dec 31 06:00–11:00