Most often in May, 26 days.
Highest follower count seen that year: 22,772.
January
Jan 1 00:00–03:00 Jan 2 00:00–12:00 Jan 7 05:00–12:00 Jan 8 03:00–12:00 Jan 9 03:00–12:00 Jan 10 03:00–12:00 Jan 12 03:00–16:00 Jan 14 03:00–11:00 Jan 15 03:00–12:00, 21:00–24:00 Jan 16 00:00–02:00, 04:00–12:00 Jan 18 03:00–12:00 Jan 19 06:00–13:00 Jan 21 03:00–12:00 Jan 22 03:00–11:00 Jan 23 03:00–12:00 Jan 24 03:00–10:00 Jan 25 03:00–12:00 Jan 26 13:00–20:00 Jan 28 04:00–12:00 Jan 29 03:00–12:00, 21:00–24:00 Jan 30 00:00–12:00 Jan 31 03:00–11:00
February
Feb 1 04:00–13:00 Feb 3 04:00–10:00 Feb 5 03:00–12:00 Feb 6 03:00–12:00 Feb 7 03:00–12:00 Feb 8 20:00–24:00 Feb 9 00:00–11:00, 13:00–18:00 Feb 11 03:00–12:00 Feb 12 03:00–12:00 Feb 13 04:00–11:00 Feb 15 10:00–21:00 Feb 17 00:00–08:00 Feb 18 06:00–15:00 Feb 20 03:00–12:00 Feb 21 06:00–15:00 Feb 22 07:00–15:00 Feb 25 06:00–09:00 Feb 26 00:00–12:00 Feb 27 04:00–12:00 Feb 28 05:00–14:00
March
Mar 4 05:00–12:00 Mar 6 04:00–11:00 Mar 7 19:00–24:00 Mar 8 00:00–03:00, 21:00–24:00 Mar 11 21:00–24:00 Mar 12 00:00–03:00 Mar 13 03:00–04:00 Mar 14 01:00–10:00 Mar 15 04:00–12:00 Mar 18 07:00–12:00 Mar 19 05:00–10:00 Mar 20 04:00–11:00 Mar 21 04:00–11:00 Mar 22 04:00–12:00 Mar 25 20:00–24:00 Mar 26 00:00–02:00, 04:00–11:00 Mar 27 03:00–11:00, 13:00–19:00 Mar 29 03:00–11:00 Mar 30 13:00–19:00 Mar 31 20:00–24:00
April
Apr 1 00:00–11:00 Apr 3 03:00–12:00 Apr 4 03:00–12:00 Apr 5 03:00–11:00 Apr 6 04:00–07:00 Apr 8 03:00–12:00 Apr 9 21:00–24:00 Apr 10 00:00–10:00 Apr 11 03:00–19:00 Apr 12 13:00–19:00 Apr 14 03:00–11:00 Apr 15 20:00–24:00 Apr 16 00:00–11:00 Apr 17 05:00–13:00 Apr 22 03:00–12:00 Apr 23 03:00–11:00 Apr 24 03:00–12:00 Apr 25 20:00–24:00 Apr 26 00:00–11:00 Apr 29 04:00–12:00
May
May 1 00:00–11:00 May 2 05:00–13:00 May 3 06:00–12:00 May 4 06:00–14:00 May 5 20:00–24:00 May 6 00:00–04:00 May 7 04:00–11:00 May 8 04:00–14:00 May 9 05:00–11:00 May 11 23:00–24:00 May 12 00:00–03:00 May 13 23:00–24:00 May 14 00:00–03:00 May 15 04:00–10:00 May 16 06:00–12:00 May 17 06:00–10:00 May 20 07:00–12:00 May 21 06:00–14:00 May 22 08:00–10:00 May 23 05:00–13:00 May 24 06:00–12:00 May 27 07:00–11:00 May 28 06:00–12:00 May 29 06:00–11:00 May 30 07:00–14:00 May 31 08:00–11:00
June
Jun 4 06:00–11:00 Jun 5 06:00–13:00 Jun 6 07:00–13:00 Jun 9 06:00–11:00 Jun 10 07:00–13:00 Jun 11 07:00–11:00 Jun 12 08:00–14:00 Jun 13 10:00–17:00 Jun 14 15:00–23:00 Jun 15 17:00–21:00 Jun 18 00:00–06:00 Jun 19 04:00–11:00 Jun 20 06:00–12:00 Jun 21 23:00–24:00 Jun 22 00:00–06:00 Jun 23 22:00–24:00 Jun 24 00:00–06:00 Jun 25 05:00–09:00 Jun 26 05:00–13:00 Jun 27 06:00–14:00 Jun 28 08:00–13:00
July
Jul 8 01:00–11:00 Jul 9 05:00–12:00 Jul 10 05:00–14:00 Jul 11 05:00–14:00 Jul 12 06:00–13:00 Jul 13 06:00–14:00 Jul 14 06:00–14:00 Jul 15 07:00–13:00 Jul 17 06:00–13:00 Jul 18 14:00–17:00 Jul 22 06:00–13:00 Jul 24 01:00–10:00 Jul 26 17:00–23:00 Jul 27 06:00–12:00 Jul 29 04:00–11:00 Jul 30 06:00–13:00 Jul 31 05:00–18:00
August
Aug 2 21:00–24:00 Aug 3 00:00–02:00 Aug 5 06:00–13:00 Aug 6 06:00–12:00 Aug 10 23:00–24:00 Aug 11 00:00–08:00 Aug 12 06:00–13:00 Aug 14 04:00–10:00 Aug 15 02:00–09:00 Aug 16 02:00–09:00 Aug 18 03:00–06:00 Aug 19 02:00–08:00 Aug 20 02:00–08:00 Aug 21 06:00–11:00 Aug 22 03:00–10:00 Aug 23 05:00–12:00 Aug 24 05:00–12:00 Aug 26 05:00–13:00 Aug 27 07:00–11:00 Aug 28 09:00–12:00 Aug 29 07:00–12:00 Aug 30 09:00–14:00
September
Sep 2 04:00–10:00 Sep 3 05:00–10:00 Sep 4 06:00–13:00 Sep 6 06:00–11:00 Sep 7 07:00–13:00 Sep 9 06:00–12:00 Sep 10 07:00–14:00 Sep 11 07:00–12:00 Sep 12 09:00–14:00 Sep 13 08:00–11:00 Sep 14 08:00–11:00 Sep 17 07:00–12:00 Sep 18 07:00–13:00 Sep 19 06:00–13:00 Sep 20 09:00–15:00 Sep 21 08:00–15:00 Sep 23 08:00–13:00 Sep 24 08:00–15:00 Sep 26 03:00–10:00 Sep 27 07:00–13:00 Sep 28 07:00–12:00 Sep 29 07:00–10:00 Sep 30 05:00–09:00
October
Oct 1 03:00–09:00 Oct 2 06:00–12:00 Oct 4 08:00–13:00 Oct 6 08:00–11:00 Oct 7 07:00–12:00 Oct 8 09:00–14:00 Oct 10 06:00–12:00 Oct 11 09:00–14:00 Oct 13 07:00–13:00 Oct 14 08:00–14:00 Oct 15 08:00–14:00 Oct 16 07:00–14:00 Oct 19 21:00–24:00 Oct 20 00:00–02:00 Oct 21 03:00–12:00 Oct 22 10:00–15:00 Oct 23 09:00–15:00 Oct 24 17:00–19:00 Oct 25 01:00–12:00 Oct 27 06:00–13:00 Oct 28 06:00–14:00 Oct 29 07:00–15:00 Oct 30 08:00–14:00 Oct 31 21:00–24:00
November
Nov 1 00:00–01:00 Nov 4 21:00–24:00 Nov 5 00:00–08:00 Nov 6 03:00–12:00 Nov 7 17:00–23:00 Nov 8 23:00–24:00 Nov 9 00:00–03:00, 21:00–24:00 Nov 10 00:00–01:00 Nov 11 02:00–11:00 Nov 12 08:00–15:00 Nov 13 07:00–17:00 Nov 14 07:00–14:00 Nov 15 09:00–16:00 Nov 18 04:00–10:00 Nov 19 10:00–17:00 Nov 20 10:00–16:00 Nov 21 08:00–13:00 Nov 22 09:00–18:00 Nov 23 14:00–17:00 Nov 25 09:00–15:00 Nov 26 08:00–14:00 Nov 27 06:00–13:00 Nov 28 04:00–11:00 Nov 29 09:00–14:00 Nov 30 07:00–14:00
December
Dec 4 05:00–11:00 Dec 6 04:00–12:00 Dec 7 10:00–17:00 Dec 8 05:00–13:00 Dec 9 07:00–15:00 Dec 10 07:00–11:00 Dec 11 07:00–11:00 Dec 12 08:00–16:00 Dec 13 08:00–14:00 Dec 14 09:00–16:00 Dec 16 06:00–07:00 Dec 17 05:00–12:00 Dec 19 02:00–09:00 Dec 20 03:00–12:00 Dec 21 03:00–10:00 Dec 22 03:00–11:00 Dec 24 05:00–12:00 Dec 26 05:00–10:00 Dec 27 06:00–12:00 Dec 28 06:00–10:00 Dec 29 07:00–12:00 Dec 30 06:00–12:00 Dec 31 07:00–12:00