Most often in January, 24 days.
Highest follower count seen that year: 18,848.
January
Jan 3 22:00–24:00 Jan 5 15:00–17:00, 20:00–24:00 Jan 6 00:00–01:00, 15:00–16:00, 18:00–23:00 Jan 7 15:00–17:00, 20:00–24:00 Jan 8 00:00–01:00, 14:00–23:00 Jan 9 20:00–24:00 Jan 10 00:00–04:00, 16:00–24:00 Jan 11 00:00–02:00, 15:00–22:00 Jan 12 16:00–20:00, 23:00–24:00 Jan 13 00:00–03:00, 21:00–24:00 Jan 14 15:00–18:00 Jan 15 01:00–04:00, 12:00–14:00 Jan 16 13:00–18:00 Jan 17 09:00–11:00 Jan 21 00:00–03:00, 21:00–24:00 Jan 22 00:00–04:00, 16:00–24:00 Jan 23 00:00–02:00, 15:00–24:00 Jan 24 00:00–02:00, 10:00–12:00 Jan 25 16:00–20:00, 22:00–24:00 Jan 26 17:00–24:00 Jan 27 00:00–02:00, 16:00–21:00 Jan 28 04:00–05:00, 15:00–24:00 Jan 29 00:00–01:00, 03:00–04:00, 15:00–24:00 Jan 30 00:00–04:00, 09:00–16:00
February
Feb 2 16:00–17:00 Feb 3 16:00–24:00 Feb 4 00:00–02:00, 23:00–24:00 Feb 5 00:00–01:00, 19:00–24:00 Feb 6 17:00–18:00, 20:00–21:00, 23:00–24:00 Feb 7 00:00–03:00, 16:00–20:00, 22:00–24:00 Feb 8 00:00–02:00 Feb 9 16:00–17:00 Feb 11 15:00–18:00, 20:00–24:00 Feb 12 00:00–02:00, 10:00–16:00 Feb 13 12:00–13:00, 17:00–23:00 Feb 14 10:00–12:00 Feb 16 13:00–22:00 Feb 17 12:00–19:00 Feb 18 12:00–17:00, 19:00–24:00 Feb 19 00:00–01:00, 16:00–17:00, 20:00–23:00 Feb 20 20:00–23:00 Feb 21 00:00–02:00, 09:00–13:00 Feb 24 13:00–16:00 Feb 25 15:00–21:00 Feb 26 15:00–17:00, 21:00–24:00 Feb 27 00:00–03:00, 10:00–18:00, 21:00–24:00 Feb 28 00:00–04:00, 10:00–17:00
March
Mar 1 01:00–04:00 Mar 2 17:00–23:00 Mar 4 16:00–18:00, 20:00–22:00 Mar 6 17:00–20:00 Mar 7 00:00–02:00, 10:00–14:00, 16:00–17:00 Mar 9 00:00–04:00, 16:00–19:00 Mar 10 10:00–17:00 Mar 12 13:00–15:00, 21:00–24:00 Mar 13 00:00–02:00, 15:00–24:00 Mar 16 16:00–22:00 Mar 18 22:00–24:00 Mar 19 00:00–02:00, 15:00–19:00 Mar 20 23:00–24:00 Mar 21 01:00–03:00, 09:00–12:00 Mar 23 14:00–23:00 Mar 24 16:00–23:00 Mar 25 15:00–24:00 Mar 26 16:00–17:00, 21:00–24:00 Mar 27 00:00–02:00, 14:00–24:00 Mar 28 00:00–02:00 Mar 30 17:00–24:00 Mar 31 16:00–18:00
April
Apr 1 00:00–02:00 Apr 4 15:00–18:00 Apr 5 18:00–24:00 Apr 6 00:00–01:00, 12:00–16:00 Apr 8 16:00–17:00 Apr 9 16:00–17:00 Apr 10 14:00–21:00 Apr 11 10:00–13:00 Apr 14 14:00–16:00, 22:00–24:00 Apr 15 00:00–02:00, 15:00–17:00, 19:00–22:00 Apr 16 23:00–24:00 Apr 17 00:00–02:00, 15:00–24:00 Apr 18 00:00–04:00, 10:00–13:00 Apr 19 14:00–17:00 Apr 20 12:00–21:00 Apr 21 14:00–15:00, 17:00–20:00 Apr 23 11:00–14:00 Apr 27 18:00–24:00 Apr 28 11:00–20:00 Apr 29 13:00–16:00 Apr 30 13:00–18:00
May
May 1 14:00–16:00, 18:00–22:00 May 4 19:00–20:00 May 5 18:00–21:00 May 6 11:00–17:00, 20:00–24:00 May 7 13:00–16:00 May 9 11:00–19:00 May 11 21:00–22:00 May 12 12:00–17:00 May 13 21:00–23:00 May 14 13:00–17:00, 19:00–20:00 May 16 16:00–17:00 May 19 18:00–23:00 May 20 11:00–20:00 May 21 11:00–13:00 May 23 09:00–12:00 May 27 13:00–17:00, 21:00–24:00 May 28 00:00–01:00, 12:00–17:00, 19:00–21:00 May 29 11:00–17:00, 19:00–22:00 May 30 09:00–13:00
June
Jun 4 08:00–14:00 Jun 5 11:00–13:00, 15:00–19:00 Jun 6 10:00–12:00 Jun 8 14:00–15:00, 19:00–24:00 Jun 9 00:00–01:00, 23:00–24:00 Jun 10 00:00–01:00, 14:00–19:00 Jun 11 13:00–17:00, 19:00–24:00 Jun 12 00:00–03:00, 10:00–18:00, 21:00–24:00 Jun 13 11:00–14:00 Jun 15 12:00–16:00, 20:00–22:00 Jun 16 12:00–16:00, 19:00–21:00 Jun 17 00:00–01:00 Jun 18 12:00–22:00 Jun 20 09:00–13:00 Jun 22 18:00–23:00 Jun 23 13:00–18:00, 22:00–24:00 Jun 24 00:00–01:00, 21:00–24:00 Jun 25 14:00–17:00, 19:00–22:00 Jun 27 10:00–12:00 Jun 30 13:00–16:00
July
Jul 4 17:00–18:00 Jul 8 15:00–17:00, 19:00–24:00 Jul 10 13:00–20:00 Jul 22 20:00–24:00 Jul 23 19:00–21:00, 23:00–24:00 Jul 24 00:00–03:00, 19:00–21:00 Jul 25 01:00–02:00, 14:00–17:00, 21:00–22:00