Most often in January, 29 days.
Highest follower count seen that year: 38,871.
January
Jan 1 00:00–04:00, 16:00–18:00, 23:00–24:00 Jan 2 00:00–02:00, 14:00–16:00, 23:00–24:00 Jan 3 00:00–01:00 Jan 5 22:00–23:00 Jan 7 00:00–01:00, 23:00–24:00 Jan 8 00:00–02:00 Jan 9 00:00–03:00 Jan 10 00:00–03:00 Jan 11 00:00–03:00 Jan 12 00:00–02:00 Jan 13 00:00–03:00 Jan 14 00:00–02:00, 16:00–19:00 Jan 15 00:00–01:00, 23:00–24:00 Jan 16 00:00–03:00, 16:00–18:00 Jan 17 00:00–03:00, 15:00–18:00 Jan 18 00:00–02:00, 17:00–18:00 Jan 19 17:00–18:00, 23:00–24:00 Jan 20 00:00–01:00, 15:00–19:00 Jan 21 01:00–02:00, 08:00–09:00, 17:00–19:00 Jan 22 00:00–02:00, 15:00–18:00 Jan 23 00:00–03:00, 14:00–18:00 Jan 24 02:00–03:00, 15:00–18:00 Jan 25 01:00–02:00, 16:00–18:00 Jan 26 12:00–14:00, 16:00–18:00 Jan 27 00:00–01:00, 15:00–19:00 Jan 28 10:00–18:00 Jan 29 00:00–02:00, 11:00–17:00 Jan 30 01:00–02:00, 13:00–18:00 Jan 31 00:00–02:00, 15:00–18:00
February
Feb 1 13:00–16:00, 23:00–24:00 Feb 2 00:00–01:00, 15:00–17:00 Feb 3 00:00–01:00, 15:00–18:00 Feb 4 00:00–02:00, 14:00–18:00, 23:00–24:00 Feb 5 00:00–01:00, 15:00–17:00, 23:00–24:00 Feb 6 17:00–19:00 Feb 7 01:00–03:00, 16:00–17:00 Feb 8 00:00–02:00, 14:00–16:00 Feb 9 00:00–02:00, 16:00–19:00 Feb 10 00:00–02:00, 14:00–16:00 Feb 11 01:00–03:00, 17:00–18:00 Feb 12 00:00–02:00 Feb 13 00:00–04:00, 14:00–19:00 Feb 14 00:00–01:00, 03:00–04:00, 15:00–19:00 Feb 15 00:00–02:00 Feb 16 00:00–02:00, 16:00–18:00 Feb 17 00:00–02:00, 17:00–18:00 Feb 18 00:00–02:00, 16:00–18:00 Feb 27 00:00–02:00, 15:00–17:00 Feb 28 00:00–02:00
March
Mar 2 00:00–01:00, 17:00–18:00 Mar 3 01:00–03:00, 14:00–17:00 Mar 4 01:00–02:00, 15:00–18:00 Mar 5 01:00–02:00 Mar 6 15:00–18:00 Mar 7 01:00–03:00, 15:00–17:00 Mar 8 01:00–02:00, 14:00–16:00 Mar 9 00:00–01:00, 23:00–24:00 Mar 10 00:00–01:00, 16:00–17:00, 23:00–24:00 Mar 11 00:00–01:00, 15:00–16:00 Mar 12 01:00–03:00, 15:00–17:00 Mar 13 00:00–03:00, 15:00–17:00 Mar 14 00:00–02:00, 17:00–18:00 Mar 15 00:00–03:00, 15:00–17:00, 23:00–24:00 Mar 16 00:00–01:00, 15:00–18:00 Mar 17 00:00–02:00, 16:00–17:00 Mar 18 00:00–02:00, 14:00–18:00 Mar 26 15:00–18:00 Mar 27 00:00–03:00, 15:00–17:00 Mar 28 14:00–18:00 Mar 29 00:00–02:00, 15:00–17:00, 23:00–24:00 Mar 30 16:00–17:00, 23:00–24:00 Mar 31 00:00–02:00, 14:00–17:00
April
Apr 1 00:00–02:00, 15:00–16:00, 23:00–24:00 Apr 2 00:00–02:00, 14:00–17:00, 23:00–24:00 Apr 3 00:00–02:00, 14:00–16:00 Apr 6 15:00–17:00, 23:00–24:00 Apr 7 00:00–01:00, 14:00–17:00, 22:00–24:00 Apr 8 00:00–01:00, 14:00–16:00, 22:00–23:00 Apr 9 00:00–01:00, 14:00–17:00, 23:00–24:00 Apr 10 00:00–01:00 Apr 13 13:00–15:00, 23:00–24:00 Apr 14 00:00–01:00, 23:00–24:00 Apr 15 00:00–01:00, 10:00–11:00, 23:00–24:00 Apr 16 00:00–01:00, 13:00–16:00, 23:00–24:00 Apr 17 00:00–02:00, 13:00–17:00, 23:00–24:00 Apr 18 00:00–01:00, 13:00–17:00, 23:00–24:00 Apr 19 00:00–01:00, 12:00–16:00, 23:00–24:00 Apr 20 00:00–01:00, 15:00–17:00, 23:00–24:00 Apr 21 00:00–01:00, 15:00–17:00, 23:00–24:00 Apr 22 00:00–01:00, 14:00–17:00, 22:00–24:00 Apr 23 00:00–01:00, 15:00–17:00 Apr 24 14:00–16:00, 23:00–24:00 Apr 25 14:00–17:00 Apr 26 15:00–17:00 Apr 27 01:00–02:00, 14:00–16:00 Apr 28 00:00–02:00, 14:00–16:00, 23:00–24:00 Apr 29 00:00–02:00, 15:00–16:00 Apr 30 14:00–16:00, 22:00–24:00
May
May 1 16:00–17:00, 23:00–24:00 May 2 00:00–01:00 May 3 00:00–02:00, 15:00–17:00, 23:00–24:00 May 4 13:00–16:00, 23:00–24:00 May 5 00:00–01:00, 15:00–16:00, 23:00–24:00 May 6 00:00–01:00, 14:00–15:00, 23:00–24:00 May 7 00:00–01:00 May 8 14:00–15:00, 23:00–24:00 May 9 00:00–01:00, 16:00–17:00 May 10 00:00–01:00, 16:00–17:00 May 11 16:00–17:00, 23:00–24:00 May 12 00:00–01:00, 15:00–16:00 May 13 13:00–15:00, 23:00–24:00 May 14 00:00–01:00, 13:00–16:00, 22:00–24:00 May 15 00:00–01:00, 13:00–14:00, 16:00–17:00 May 17 22:00–24:00 May 18 15:00–16:00, 23:00–24:00 May 19 00:00–01:00, 14:00–15:00, 23:00–24:00 May 20 00:00–01:00, 16:00–18:00 May 21 23:00–24:00 May 22 00:00–01:00, 14:00–17:00, 23:00–24:00 May 23 00:00–01:00, 16:00–17:00, 23:00–24:00 May 24 00:00–02:00, 15:00–17:00 May 25 00:00–02:00, 15:00–17:00, 23:00–24:00 May 26 00:00–01:00, 15:00–17:00, 23:00–24:00 May 27 00:00–02:00 May 28 00:00–02:00, 15:00–18:00, 23:00–24:00 May 29 00:00–01:00, 14:00–17:00, 23:00–24:00 May 30 00:00–02:00
June
Jun 2 00:00–01:00, 16:00–17:00, 23:00–24:00 Jun 3 00:00–01:00, 14:00–16:00 Jun 4 00:00–02:00 Jun 5 00:00–02:00, 14:00–16:00 Jun 7 01:00–03:00, 18:00–19:00 Jun 8 01:00–03:00, 15:00–16:00, 23:00–24:00 Jun 9 00:00–01:00, 15:00–16:00 Jun 10 00:00–01:00, 16:00–18:00 Jun 11 00:00–01:00, 16:00–18:00 Jun 12 00:00–01:00, 16:00–18:00 Jun 13 00:00–02:00, 16:00–19:00 Jun 15 15:00–17:00, 22:00–24:00 Jun 16 00:00–01:00, 15:00–17:00, 23:00–24:00 Jun 17 15:00–17:00, 23:00–24:00 Jun 18 15:00–16:00 Jun 19 14:00–16:00, 23:00–24:00 Jun 20 22:00–24:00 Jun 21 00:00–02:00, 16:00–17:00, 23:00–24:00 Jun 22 00:00–01:00, 16:00–17:00 Jun 23 00:00–01:00, 16:00–17:00, 23:00–24:00 Jun 24 00:00–01:00, 15:00–16:00 Jun 25 00:00–01:00, 14:00–16:00 Jun 26 15:00–16:00, 23:00–24:00 Jun 27 22:00–24:00 Jun 28 14:00–16:00, 23:00–24:00 Jun 29 00:00–01:00, 14:00–16:00, 23:00–24:00 Jun 30 00:00–01:00, 14:00–15:00, 23:00–24:00
July
Jul 1 00:00–01:00, 23:00–24:00 Jul 2 00:00–01:00 Jul 4 00:00–01:00, 16:00–17:00 Jul 5 01:00–03:00, 17:00–18:00, 23:00–24:00 Jul 6 00:00–02:00, 23:00–24:00 Jul 7 00:00–01:00, 23:00–24:00 Jul 8 00:00–02:00, 15:00–16:00, 23:00–24:00 Jul 9 00:00–01:00 Jul 13 23:00–24:00 Jul 14 15:00–16:00 Jul 15 00:00–02:00, 16:00–17:00 Jul 16 00:00–02:00, 15:00–17:00, 23:00–24:00 Jul 17 00:00–02:00 Jul 18 00:00–02:00, 16:00–17:00, 23:00–24:00 Jul 19 23:00–24:00 Jul 20 14:00–16:00, 19:00–20:00 Jul 21 01:00–02:00, 15:00–17:00, 23:00–24:00 Jul 22 00:00–01:00, 14:00–17:00, 23:00–24:00 Jul 23 01:00–02:00, 18:00–21:00 Jul 24 16:00–17:00 Jul 25 01:00–02:00, 16:00–17:00, 22:00–24:00 Jul 26 00:00–01:00, 15:00–16:00, 23:00–24:00 Jul 27 00:00–01:00