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