Most often in March, 30 days.
Highest follower count seen that year: 7,207.
January
Jan 2 18:00–21:00 Jan 3 12:00–22:00 Jan 4 12:00–19:00 Jan 5 11:00–18:00 Jan 6 11:00–21:00 Jan 7 15:00–21:00 Jan 8 11:00–20:00 Jan 10 12:00–20:00 Jan 11 11:00–19:00 Jan 12 12:00–19:00 Jan 13 15:00–22:00 Jan 14 13:00–21:00 Jan 15 15:00–24:00 Jan 17 11:00–18:00 Jan 18 11:00–19:00 Jan 19 13:00–20:00 Jan 20 12:00–20:00 Jan 21 12:00–19:00 Jan 22 12:00–19:00 Jan 24 11:00–19:00 Jan 25 13:00–20:00 Jan 26 12:00–19:00 Jan 27 12:00–16:00 Jan 28 12:00–19:00 Jan 29 12:00–23:00 Jan 30 12:00–20:00
February
Feb 1 13:00–19:00 Feb 3 11:00–18:00 Feb 4 11:00–19:00 Feb 5 17:00–21:00 Feb 6 17:00–24:00 Feb 7 00:00–04:00, 11:00–18:00, 20:00–22:00 Feb 9 15:00–24:00 Feb 10 17:00–24:00 Feb 11 00:00–01:00, 17:00–24:00 Feb 12 15:00–19:00, 22:00–24:00 Feb 13 00:00–01:00, 17:00–24:00 Feb 14 01:00–02:00, 17:00–24:00 Feb 15 13:00–20:00 Feb 16 20:00–24:00 Feb 17 00:00–02:00, 17:00–24:00 Feb 18 18:00–24:00 Feb 19 00:00–01:00 Feb 21 19:00–24:00 Feb 22 00:00–02:00, 15:00–23:00 Feb 23 17:00–24:00 Feb 24 17:00–24:00 Feb 25 16:00–23:00 Feb 26 15:00–19:00 Feb 27 17:00–24:00 Feb 28 16:00–24:00
March
Mar 1 00:00–03:00 Mar 2 18:00–24:00 Mar 3 00:00–01:00 Mar 4 17:00–19:00 Mar 5 17:00–22:00 Mar 6 17:00–24:00 Mar 7 17:00–24:00 Mar 8 00:00–01:00, 14:00–21:00 Mar 9 13:00–20:00 Mar 10 20:00–24:00 Mar 11 00:00–03:00, 13:00–24:00 Mar 12 00:00–04:00, 14:00–24:00 Mar 13 00:00–03:00, 16:00–19:00, 21:00–23:00 Mar 14 15:00–24:00 Mar 15 00:00–02:00, 14:00–19:00 Mar 16 19:00–24:00 Mar 17 00:00–03:00, 20:00–24:00 Mar 18 01:00–03:00, 21:00–24:00 Mar 19 00:00–03:00, 20:00–24:00 Mar 20 00:00–02:00 Mar 21 11:00–18:00 Mar 23 16:00–24:00 Mar 24 00:00–03:00, 18:00–24:00 Mar 25 00:00–02:00, 20:00–24:00 Mar 26 00:00–03:00, 20:00–24:00 Mar 27 00:00–03:00 Mar 28 20:00–24:00 Mar 29 00:00–03:00 Mar 30 21:00–24:00 Mar 31 00:00–03:00, 15:00–19:00, 23:00–24:00
April
Apr 1 00:00–04:00, 21:00–24:00 Apr 2 00:00–03:00, 20:00–24:00 Apr 3 00:00–03:00 Apr 6 22:00–24:00 Apr 8 21:00–24:00 Apr 9 00:00–03:00, 23:00–24:00 Apr 10 00:00–03:00, 14:00–21:00 Apr 11 21:00–24:00 Apr 12 00:00–03:00, 11:00–19:00 Apr 13 20:00–24:00 Apr 14 00:00–03:00, 21:00–24:00 Apr 15 00:00–24:00 Apr 16 00:00–03:00 Apr 18 22:00–24:00 Apr 19 00:00–02:00 Apr 20 22:00–24:00 Apr 21 00:00–04:00, 09:00–23:00 Apr 25 21:00–24:00 Apr 26 00:00–03:00, 18:00–22:00 Apr 27 22:00–24:00 Apr 28 00:00–08:00, 10:00–16:00, 18:00–24:00 Apr 29 21:00–24:00 Apr 30 00:00–04:00
May
May 3 00:00–03:00 May 4 22:00–24:00 May 5 00:00–03:00, 21:00–24:00 May 6 00:00–02:00, 21:00–24:00 May 7 00:00–03:00 May 8 19:00–24:00 May 9 00:00–01:00, 22:00–24:00 May 10 00:00–03:00, 15:00–19:00 May 12 18:00–24:00 May 13 01:00–03:00, 17:00–23:00 May 14 22:00–24:00 May 15 00:00–03:00, 21:00–23:00 May 16 01:00–02:00 May 19 21:00–24:00 May 20 00:00–03:00 May 21 01:00–03:00, 20:00–24:00 May 22 01:00–03:00, 21:00–24:00 May 23 00:00–02:00, 21:00–24:00 May 24 00:00–03:00 May 26 21:00–24:00 May 27 00:00–04:00 May 28 00:00–08:00, 18:00–24:00 May 29 00:00–03:00, 21:00–23:00 May 30 00:00–04:00, 21:00–24:00 May 31 00:00–03:00, 12:00–20:00
June
Jun 1 20:00–24:00 Jun 2 00:00–01:00 Jun 5 21:00–24:00 Jun 6 00:00–04:00, 20:00–24:00 Jun 7 00:00–04:00 Jun 8 19:00–24:00 Jun 9 00:00–02:00, 23:00–24:00 Jun 10 00:00–03:00 Jun 11 18:00–24:00 Jun 12 00:00–03:00 Jun 15 19:00–24:00 Jun 16 00:00–01:00, 19:00–24:00 Jun 17 00:00–02:00, 20:00–24:00 Jun 18 01:00–02:00, 20:00–24:00 Jun 19 00:00–01:00, 21:00–23:00 Jun 20 00:00–03:00, 19:00–24:00 Jun 21 00:00–03:00 Jun 23 20:00–24:00 Jun 24 00:00–03:00, 19:00–21:00, 23:00–24:00 Jun 25 00:00–02:00, 21:00–24:00 Jun 26 00:00–03:00 Jun 28 01:00–16:00 Jun 30 20:00–24:00
July
Jul 1 00:00–03:00, 20:00–24:00 Jul 2 00:00–02:00, 20:00–24:00 Jul 3 00:00–03:00, 20:00–24:00 Jul 4 00:00–03:00, 18:00–24:00 Jul 5 00:00–12:00 Jul 6 19:00–24:00 Jul 7 00:00–02:00, 21:00–24:00 Jul 8 00:00–03:00, 20:00–24:00 Jul 9 00:00–02:00, 18:00–24:00 Jul 10 00:00–01:00 Jul 11 21:00–22:00 Jul 12 00:00–03:00 Jul 13 20:00–24:00 Jul 14 00:00–03:00, 22:00–24:00 Jul 15 00:00–03:00, 22:00–24:00 Jul 16 00:00–04:00, 21:00–24:00 Jul 17 00:00–03:00 Jul 18 23:00–24:00 Jul 19 00:00–11:00 Jul 21 19:00–24:00 Jul 22 00:00–02:00, 23:00–24:00 Jul 23 01:00–03:00 Jul 24 00:00–01:00, 22:00–23:00 Jul 25 00:00–05:00