Most often in March, 30 days.
Highest follower count seen that year: 73,533.
January
Jan 5 14:00–23:00 Jan 6 19:00–24:00 Jan 7 00:00–05:00 Jan 8 17:00–24:00 Jan 9 00:00–03:00 Jan 10 15:00–24:00 Jan 11 00:00–01:00, 16:00–24:00 Jan 12 00:00–02:00, 23:00–24:00 Jan 13 00:00–08:00 Jan 14 16:00–24:00 Jan 15 00:00–02:00, 17:00–24:00 Jan 16 00:00–03:00 Jan 17 16:00–24:00 Jan 18 00:00–02:00, 16:00–24:00 Jan 19 00:00–02:00, 17:00–24:00 Jan 20 00:00–03:00 Jan 21 14:00–24:00 Jan 22 00:00–01:00, 14:00–24:00 Jan 23 00:00–01:00 Jan 24 19:00–24:00 Jan 25 01:00–05:00, 17:00–24:00 Jan 26 00:00–03:00, 17:00–24:00 Jan 27 00:00–03:00 Jan 28 16:00–24:00 Jan 29 00:00–03:00, 17:00–23:00 Jan 30 00:00–04:00 Jan 31 17:00–23:00
February
Feb 1 00:00–04:00, 17:00–23:00 Feb 2 00:00–04:00, 20:00–24:00 Feb 3 00:00–01:00, 03:00–07:00 Feb 4 18:00–23:00 Feb 5 02:00–06:00, 17:00–24:00 Feb 6 00:00–02:00 Feb 7 18:00–24:00 Feb 8 02:00–06:00, 20:00–24:00 Feb 9 00:00–06:00, 20:00–24:00 Feb 10 00:00–05:00 Feb 11 19:00–23:00 Feb 12 00:00–06:00, 20:00–24:00 Feb 13 00:00–07:00 Feb 14 19:00–24:00 Feb 15 00:00–05:00, 19:00–24:00 Feb 16 00:00–06:00, 20:00–24:00 Feb 17 00:00–06:00 Feb 18 18:00–24:00 Feb 19 00:00–03:00, 18:00–24:00 Feb 20 00:00–03:00 Feb 21 16:00–24:00 Feb 22 00:00–03:00, 20:00–24:00 Feb 23 00:00–06:00, 17:00–23:00 Feb 24 02:00–05:00 Feb 25 20:00–24:00 Feb 26 00:00–05:00, 19:00–24:00 Feb 27 00:00–04:00 Feb 28 21:00–22:00
March
Mar 1 00:00–08:00, 20:00–24:00 Mar 2 00:00–01:00, 03:00–07:00, 18:00–24:00 Mar 3 00:00–04:00 Mar 4 19:00–24:00 Mar 5 00:00–04:00, 16:00–24:00 Mar 6 00:00–03:00 Mar 7 17:00–24:00 Mar 8 00:00–05:00, 19:00–24:00 Mar 9 00:00–05:00, 18:00–23:00 Mar 10 00:00–05:00 Mar 11 18:00–24:00 Mar 12 01:00–05:00, 18:00–23:00 Mar 13 00:00–05:00 Mar 14 18:00–23:00 Mar 15 01:00–05:00, 19:00–24:00 Mar 16 00:00–05:00, 20:00–24:00 Mar 17 00:00–06:00, 19:00–22:00 Mar 18 00:00–07:00, 18:00–24:00 Mar 19 00:00–02:00 Mar 21 18:00–24:00 Mar 22 02:00–06:00, 18:00–24:00 Mar 23 03:00–07:00, 21:00–24:00 Mar 24 00:00–07:00 Mar 25 18:00–21:00 Mar 26 02:00–09:00, 21:00–24:00 Mar 27 03:00–06:00 Mar 28 23:00–24:00 Mar 29 00:00–08:00, 18:00–22:00 Mar 30 03:00–08:00, 18:00–24:00 Mar 31 05:00–09:00, 19:00–24:00
April
Apr 1 00:00–01:00, 05:00–08:00 Apr 2 17:00–23:00 Apr 3 03:00–07:00 Apr 4 17:00–22:00 Apr 5 01:00–05:00, 17:00–24:00 Apr 6 05:00–09:00, 18:00–24:00 Apr 7 00:00–04:00 Apr 8 17:00–22:00 Apr 9 00:00–06:00, 19:00–22:00 Apr 10 05:00–10:00 Apr 11 19:00–24:00 Apr 12 01:00–07:00, 19:00–24:00 Apr 13 00:00–05:00, 19:00–24:00 Apr 14 00:00–06:00 Apr 15 08:00–18:00 Apr 16 04:00–15:00 Apr 18 04:00–15:00 Apr 19 11:00–19:00 Apr 20 08:00–15:00 Apr 22 04:00–15:00 Apr 23 05:00–16:00 Apr 25 04:00–15:00 Apr 26 05:00–16:00 Apr 27 05:00–15:00 Apr 29 05:00–10:00, 12:00–16:00 Apr 30 10:00–19:00
May
May 2 06:00–15:00 May 3 06:00–16:00 May 4 05:00–14:00 May 6 09:00–14:00 May 9 06:00–16:00 May 10 07:00–15:00 May 11 07:00–18:00 May 12 06:00–11:00, 13:00–18:00 May 13 06:00–11:00, 13:00–16:00 May 15 05:00–16:00 May 16 06:00–11:00, 13:00–17:00 May 17 09:00–19:00 May 18 08:00–19:00 May 20 07:00–17:00 May 21 06:00–14:00 May 23 06:00–16:00 May 24 06:00–16:00 May 25 06:00–16:00 May 26 07:00–15:00 May 27 06:00–16:00 May 30 05:00–15:00 May 31 05:00–15:00
June
Jun 1 06:00–15:00 Jun 3 05:00–15:00 Jun 4 06:00–15:00 Jun 6 07:00–16:00 Jun 7 07:00–17:00 Jun 8 05:00–09:00, 11:00–15:00 Jun 10 06:00–15:00 Jun 11 04:00–13:00 Jun 12 06:00–16:00 Jun 13 08:00–18:00 Jun 15 06:00–16:00 Jun 16 06:00–16:00 Jun 18 06:00–16:00 Jun 19 06:00–16:00 Jun 21 06:00–16:00 Jun 22 06:00–16:00 Jun 30 06:00–16:00
July
Jul 1 06:00–16:00 Jul 3 05:00–15:00 Jul 4 04:00–14:00 Jul 6 06:00–15:00 Jul 7 05:00–15:00 Jul 9 06:00–15:00 Jul 10 05:00–15:00 Jul 12 06:00–15:00 Jul 13 06:00–15:00 Jul 14 05:00–15:00 Jul 16 06:00–16:00 Jul 17 06:00–15:00 Jul 19 06:00–16:00 Jul 20 06:00–15:00 Jul 21 06:00–16:00 Jul 23 06:00–16:00 Jul 24 06:00–16:00 Jul 26 06:00–16:00 Jul 27 07:00–16:00 Jul 28 05:00–15:00 Jul 30 06:00–15:00
August
Aug 1 06:00–16:00 Aug 2 06:00–16:00 Aug 3 06:00–14:00 Aug 5 06:00–15:00 Aug 6 07:00–16:00 Aug 8 06:00–16:00 Aug 9 04:00–12:00 Aug 11 06:00–10:00, 12:00–16:00 Aug 12 06:00–15:00 Aug 13 06:00–14:00 Aug 15 07:00–17:00 Aug 16 07:00–16:00 Aug 17 06:00–16:00 Aug 18 05:00–15:00 Aug 19 07:00–16:00 Aug 23 08:00–17:00 Aug 24 04:00–13:00 Aug 25 05:00–14:00 Aug 26 06:00–16:00 Aug 27 06:00–16:00 Aug 29 06:00–16:00 Aug 30 06:00–16:00 Aug 31 06:00–16:00
September
Sep 2 05:00–15:00 Sep 3 06:00–15:00 Sep 5 06:00–16:00 Sep 6 07:00–17:00 Sep 7 08:00–17:00 Sep 9 05:00–14:00 Sep 10 07:00–16:00 Sep 12 07:00–18:00 Sep 13 07:00–16:00 Sep 14 07:00–17:00 Sep 17 18:00–23:00 Sep 18 00:00–03:00, 16:00–24:00 Sep 19 00:00–04:00, 18:00–24:00 Sep 20 00:00–03:00, 18:00–24:00 Sep 21 00:00–03:00, 17:00–24:00 Sep 22 00:00–03:00 Sep 23 18:00–24:00 Sep 24 00:00–03:00, 17:00–24:00 Sep 25 00:00–02:00, 17:00–24:00 Sep 26 00:00–03:00 Sep 27 18:00–24:00 Sep 28 00:00–03:00, 17:00–24:00 Sep 29 00:00–03:00 Sep 30 17:00–24:00
October
Oct 1 00:00–02:00, 19:00–24:00 Oct 2 00:00–05:00, 18:00–24:00 Oct 3 00:00–03:00 Oct 4 14:00–24:00 Oct 5 17:00–24:00 Oct 6 00:00–03:00 Oct 7 15:00–19:00, 21:00–24:00 Oct 8 00:00–02:00, 19:00–24:00 Oct 9 00:00–05:00, 14:00–23:00 Oct 11 16:00–24:00 Oct 12 00:00–02:00 Oct 13 18:00–22:00 Oct 14 00:00–04:00, 18:00–21:00
November
Nov 12 05:00–14:00 Nov 14 04:00–14:00 Nov 15 05:00–14:00 Nov 16 05:00–15:00 Nov 17 05:00–13:00 Nov 19 05:00–15:00 Nov 21 07:00–16:00 Nov 22 05:00–14:00 Nov 23 05:00–14:00 Nov 25 05:00–15:00 Nov 28 05:00–15:00 Nov 29 05:00–15:00 Nov 30 07:00–16:00
December
Dec 1 05:00–15:00 Dec 3 06:00–15:00 Dec 4 05:00–14:00 Dec 5 06:00–15:00 Dec 6 04:00–13:00 Dec 8 07:00–17:00 Dec 9 06:00–15:00 Dec 10 07:00–15:00 Dec 12 07:00–16:00 Dec 13 07:00–16:00 Dec 14 07:00–16:00 Dec 15 05:00–14:00 Dec 17 05:00–14:00 Dec 19 07:00–15:00 Dec 20 06:00–15:00 Dec 21 05:00–14:00 Dec 22 05:00–14:00 Dec 24 05:00–14:00 Dec 25 05:00–15:00 Dec 26 06:00–15:00 Dec 27 06:00–15:00 Dec 28 05:00–14:00 Dec 29 06:00–14:00 Dec 30 05:00–14:00