Most often in January, 29 days.
Highest follower count seen that year: 8,981.
January
Jan 1 02:00–05:00, 12:00–17:00, 22:00–24:00 Jan 3 12:00–13:00 Jan 4 13:00–16:00 Jan 5 09:00–11:00, 13:00–15:00 Jan 6 12:00–14:00 Jan 7 10:00–13:00 Jan 8 09:00–12:00, 14:00–16:00 Jan 9 11:00–12:00, 14:00–15:00 Jan 10 22:00–24:00 Jan 11 00:00–01:00, 13:00–15:00 Jan 12 14:00–17:00 Jan 13 10:00–13:00 Jan 14 12:00–14:00, 17:00–18:00 Jan 15 12:00–13:00, 15:00–16:00 Jan 16 11:00–16:00 Jan 17 11:00–15:00 Jan 18 12:00–17:00 Jan 19 01:00–02:00, 10:00–12:00, 17:00–18:00 Jan 20 12:00–13:00 Jan 21 11:00–16:00 Jan 22 13:00–14:00 Jan 23 09:00–11:00, 13:00–18:00 Jan 24 11:00–17:00 Jan 25 12:00–15:00 Jan 26 12:00–16:00 Jan 27 11:00–12:00 Jan 28 12:00–14:00 Jan 29 11:00–14:00 Jan 31 13:00–14:00, 18:00–19:00
February
Feb 1 00:00–01:00, 14:00–15:00, 18:00–19:00 Feb 2 11:00–16:00 Feb 3 12:00–14:00 Feb 4 10:00–12:00 Feb 5 10:00–14:00 Feb 6 10:00–11:00, 13:00–14:00 Feb 8 00:00–02:00, 11:00–15:00 Feb 9 06:00–10:00 Feb 11 11:00–12:00, 16:00–17:00 Feb 12 11:00–13:00, 15:00–16:00, 18:00–19:00 Feb 13 10:00–14:00 Feb 14 12:00–14:00 Feb 15 11:00–14:00, 16:00–18:00 Feb 16 12:00–14:00, 16:00–17:00 Feb 17 16:00–17:00 Feb 18 10:00–13:00 Feb 19 11:00–13:00, 15:00–19:00 Feb 20 10:00–14:00 Feb 22 01:00–04:00, 12:00–14:00, 17:00–19:00 Feb 23 08:00–13:00 Feb 26 10:00–14:00 Feb 27 09:00–13:00
March
Mar 1 11:00–16:00 Mar 2 10:00–12:00, 14:00–15:00 Mar 3 10:00–13:00 Mar 4 13:00–14:00, 17:00–18:00 Mar 5 10:00–13:00, 15:00–16:00, 18:00–20:00 Mar 6 10:00–13:00 Mar 7 11:00–14:00, 19:00–20:00 Mar 8 09:00–11:00 Mar 9 09:00–13:00, 18:00–19:00 Mar 10 12:00–13:00, 16:00–18:00 Mar 11 11:00–13:00 Mar 12 14:00–18:00 Mar 14 11:00–14:00, 22:00–24:00 Mar 15 00:00–01:00, 12:00–15:00 Mar 16 10:00–11:00, 14:00–16:00 Mar 17 10:00–14:00, 16:00–18:00 Mar 18 11:00–13:00 Mar 21 11:00–13:00, 15:00–16:00, 18:00–19:00 Mar 22 15:00–17:00, 19:00–21:00 Mar 23 16:00–22:00 Mar 24 10:00–11:00 Mar 25 12:00–14:00, 18:00–19:00 Mar 26 11:00–13:00 Mar 27 11:00–12:00, 16:00–19:00 Mar 28 10:00–12:00, 14:00–16:00 Mar 29 14:00–16:00 Mar 30 08:00–12:00, 15:00–17:00 Mar 31 12:00–14:00
April
Apr 2 12:00–14:00, 16:00–17:00 Apr 3 12:00–16:00 Apr 4 12:00–15:00, 18:00–19:00 Apr 5 22:00–23:00 Apr 6 02:00–06:00 Apr 7 10:00–12:00 Apr 8 11:00–14:00 Apr 9 11:00–12:00 Apr 10 10:00–14:00 Apr 11 10:00–16:00 Apr 12 12:00–16:00 Apr 14 10:00–13:00, 15:00–16:00 Apr 15 11:00–12:00, 15:00–19:00 Apr 16 12:00–16:00, 18:00–19:00 Apr 17 10:00–14:00, 17:00–18:00 Apr 18 13:00–15:00 Apr 19 01:00–03:00, 11:00–19:00 Apr 20 12:00–13:00, 16:00–17:00 Apr 21 10:00–13:00 Apr 22 16:00–19:00 Apr 23 08:00–10:00 Apr 24 12:00–13:00, 16:00–17:00 Apr 25 14:00–17:00 Apr 26 15:00–18:00 Apr 27 00:00–03:00, 10:00–12:00 Apr 28 12:00–15:00, 17:00–18:00 Apr 29 11:00–12:00, 15:00–16:00 Apr 30 11:00–13:00, 17:00–19:00
May
May 1 12:00–13:00 May 2 00:00–01:00, 13:00–14:00 May 3 15:00–16:00, 23:00–24:00 May 4 00:00–03:00, 12:00–13:00 May 5 01:00–03:00, 10:00–12:00 May 7 13:00–14:00 May 8 10:00–11:00 May 9 10:00–12:00 May 10 11:00–15:00 May 11 07:00–12:00 May 13 11:00–13:00, 19:00–20:00 May 14 11:00–12:00, 14:00–15:00 May 15 13:00–14:00, 17:00–19:00 May 16 00:00–01:00, 13:00–15:00 May 17 13:00–15:00, 22:00–24:00 May 18 00:00–01:00, 11:00–14:00 May 20 10:00–12:00 May 21 10:00–13:00 May 22 13:00–18:00 May 23 13:00–15:00, 23:00–24:00 May 24 00:00–01:00, 14:00–18:00 May 25 11:00–13:00, 15:00–16:00 May 26 11:00–17:00 May 27 11:00–14:00 May 28 10:00–14:00 May 29 11:00–13:00, 15:00–16:00 May 31 01:00–02:00, 10:00–14:00, 22:00–23:00
June
Jun 1 12:00–15:00, 18:00–19:00 Jun 2 14:00–16:00 Jun 3 10:00–16:00 Jun 4 11:00–19:00 Jun 5 12:00–14:00 Jun 7 11:00–15:00 Jun 8 00:00–03:00, 11:00–17:00 Jun 9 10:00–17:00 Jun 11 11:00–18:00 Jun 12 13:00–20:00 Jun 13 10:00–13:00 Jun 15 13:00–18:00 Jun 16 11:00–12:00 Jun 17 11:00–12:00 Jun 20 01:00–02:00, 10:00–16:00, 22:00–23:00 Jun 21 11:00–18:00 Jun 22 10:00–15:00 Jun 24 11:00–13:00, 16:00–20:00 Jun 25 10:00–12:00, 19:00–22:00 Jun 26 11:00–14:00, 17:00–18:00 Jun 27 00:00–02:00, 15:00–16:00, 22:00–23:00 Jun 28 00:00–02:00, 13:00–18:00 Jun 29 00:00–01:00, 19:00–24:00 Jun 30 08:00–10:00, 12:00–13:00
July
Jul 2 13:00–16:00 Jul 3 12:00–14:00, 16:00–20:00 Jul 4 14:00–19:00 Jul 5 14:00–20:00 Jul 6 16:00–17:00 Jul 7 19:00–23:00 Jul 8 14:00–17:00 Jul 10 02:00–03:00, 14:00–16:00, 21:00–24:00 Jul 11 01:00–02:00, 13:00–16:00, 18:00–19:00 Jul 12 14:00–19:00 Jul 13 00:00–02:00, 16:00–21:00 Jul 14 00:00–02:00, 11:00–13:00 Jul 16 17:00–24:00 Jul 17 14:00–16:00 Jul 18 17:00–19:00 Jul 19 00:00–03:00, 16:00–19:00, 22:00–24:00 Jul 20 00:00–01:00, 19:00–20:00 Jul 21 11:00–13:00, 15:00–17:00 Jul 22 12:00–15:00, 17:00–19:00 Jul 23 12:00–14:00 Jul 24 00:00–02:00, 11:00–13:00 Jul 25 18:00–20:00 Jul 26 13:00–14:00, 15:00–18:00 Jul 27 01:00–02:00