Most often in April, 29 days.
Highest follower count seen that year: 13,446.
January
Jan 2 13:00–23:00 Jan 3 12:00–17:00, 19:00–21:00 Jan 4 12:00–18:00, 20:00–24:00 Jan 5 12:00–16:00, 18:00–21:00 Jan 7 20:00–24:00 Jan 8 14:00–24:00 Jan 9 11:00–18:00, 20:00–24:00 Jan 10 17:00–23:00 Jan 11 13:00–22:00 Jan 12 11:00–15:00, 17:00–18:00, 20:00–21:00 Jan 13 11:00–17:00 Jan 14 15:00–18:00, 21:00–23:00 Jan 15 12:00–19:00, 21:00–24:00 Jan 16 14:00–21:00 Jan 17 14:00–19:00, 22:00–24:00 Jan 18 20:00–22:00 Jan 19 19:00–24:00 Jan 21 12:00–24:00 Jan 22 12:00–24:00 Jan 23 14:00–19:00 Jan 24 14:00–18:00, 20:00–22:00 Jan 25 14:00–20:00, 22:00–24:00 Jan 26 14:00–19:00, 22:00–24:00 Jan 28 15:00–19:00, 23:00–24:00 Jan 29 14:00–22:00 Jan 30 14:00–20:00, 22:00–24:00 Jan 31 00:00–01:00, 14:00–18:00, 21:00–22:00
February
Feb 1 20:00–24:00 Feb 2 21:00–24:00 Feb 3 00:00–01:00, 13:00–19:00 Feb 4 14:00–17:00, 20:00–22:00 Feb 5 14:00–21:00 Feb 6 14:00–24:00 Feb 7 14:00–24:00 Feb 8 14:00–23:00 Feb 9 14:00–21:00 Feb 11 13:00–21:00 Feb 12 15:00–18:00 Feb 13 14:00–22:00 Feb 14 14:00–22:00 Feb 15 19:00–23:00 Feb 16 16:00–24:00 Feb 17 13:00–18:00 Feb 18 14:00–21:00 Feb 19 13:00–22:00 Feb 20 14:00–22:00 Feb 21 11:00–19:00 Feb 22 13:00–17:00, 20:00–23:00 Feb 24 01:00–05:00 Feb 26 03:00–08:00 Feb 27 04:00–08:00 Feb 28 02:00–07:00
March
Mar 1 02:00–04:00, 21:00–24:00 Mar 3 01:00–05:00 Mar 5 02:00–07:00 Mar 6 02:00–04:00 Mar 7 02:00–07:00, 15:00–20:00 Mar 8 19:00–24:00 Mar 9 00:00–01:00 Mar 10 02:00–08:00 Mar 11 02:00–05:00 Mar 12 02:00–10:00 Mar 13 03:00–09:00 Mar 14 03:00–08:00, 14:00–19:00 Mar 15 22:00–24:00 Mar 16 00:00–02:00 Mar 17 03:00–08:00 Mar 18 02:00–08:00 Mar 19 04:00–07:00 Mar 21 04:00–08:00, 16:00–18:00 Mar 22 02:00–07:00, 15:00–21:00 Mar 24 02:00–06:00, 12:00–17:00 Mar 26 02:00–06:00, 12:00–14:00 Mar 27 02:00–05:00, 13:00–16:00 Mar 28 02:00–06:00, 14:00–19:00 Mar 29 03:00–08:00, 15:00–19:00 Mar 31 10:00–19:00
April
Apr 1 11:00–18:00 Apr 2 10:00–19:00 Apr 3 14:00–17:00 Apr 4 11:00–19:00 Apr 5 12:00–19:00 Apr 6 11:00–18:00 Apr 7 11:00–18:00 Apr 8 12:00–19:00 Apr 9 11:00–17:00 Apr 10 11:00–18:00 Apr 11 11:00–17:00 Apr 12 12:00–17:00 Apr 13 12:00–18:00 Apr 15 11:00–18:00 Apr 16 12:00–19:00 Apr 17 11:00–18:00 Apr 18 11:00–18:00 Apr 19 12:00–18:00 Apr 20 11:00–18:00 Apr 21 11:00–15:00 Apr 22 11:00–18:00 Apr 23 16:00–17:00 Apr 24 12:00–19:00 Apr 25 12:00–19:00 Apr 26 11:00–18:00 Apr 27 11:00–17:00 Apr 28 12:00–18:00 Apr 29 11:00–18:00 Apr 30 12:00–17:00
May
May 1 12:00–17:00 May 2 11:00–13:00, 15:00–16:00 May 3 11:00–20:00 May 4 12:00–16:00 May 5 11:00–17:00 May 6 12:00–15:00 May 7 12:00–17:00 May 9 11:00–13:00 May 11 14:00–16:00 May 16 13:00–18:00 May 17 12:00–15:00, 20:00–23:00 May 18 15:00–18:00 May 20 16:00–17:00 May 21 16:00–18:00 May 22 13:00–17:00 May 23 13:00–16:00, 18:00–19:00 May 24 14:00–19:00 May 25 13:00–16:00 May 26 12:00–18:00 May 27 14:00–18:00 May 28 11:00–19:00 May 29 11:00–17:00 May 30 10:00–17:00 May 31 12:00–15:00, 19:00–22:00
June
Jun 1 13:00–16:00 Jun 2 11:00–13:00, 15:00–16:00 Jun 3 12:00–14:00, 16:00–17:00 Jun 4 13:00–19:00 Jun 5 13:00–20:00 Jun 6 12:00–16:00, 18:00–19:00 Jun 7 12:00–17:00, 21:00–23:00 Jun 8 00:00–02:00, 14:00–16:00, 18:00–19:00 Jun 9 21:00–23:00 Jun 10 00:00–01:00, 16:00–18:00 Jun 11 12:00–18:00 Jun 13 13:00–17:00 Jun 15 12:00–17:00 Jun 16 14:00–17:00, 19:00–21:00 Jun 17 15:00–16:00, 19:00–22:00 Jun 18 18:00–19:00 Jun 19 13:00–17:00 Jun 20 13:00–16:00, 18:00–21:00 Jun 21 13:00–22:00 Jun 22 14:00–16:00, 18:00–20:00 Jun 24 14:00–15:00 Jun 25 14:00–17:00 Jun 26 14:00–15:00, 19:00–20:00 Jun 27 13:00–17:00 Jun 28 13:00–16:00 Jun 29 14:00–18:00, 20:00–22:00
July
Jul 1 12:00–16:00, 19:00–22:00 Jul 2 14:00–17:00 Jul 3 14:00–17:00 Jul 4 15:00–16:00, 18:00–21:00 Jul 5 13:00–18:00, 20:00–21:00 Jul 6 13:00–16:00, 19:00–22:00 Jul 7 17:00–18:00 Jul 8 21:00–23:00 Jul 9 00:00–01:00, 20:00–24:00 Jul 10 00:00–01:00, 22:00–24:00 Jul 11 00:00–01:00, 14:00–17:00, 19:00–22:00 Jul 12 14:00–16:00, 19:00–22:00 Jul 13 13:00–17:00, 19:00–21:00 Jul 14 22:00–23:00 Jul 15 01:00–02:00, 21:00–24:00 Jul 16 00:00–02:00, 20:00–24:00 Jul 17 00:00–01:00, 16:00–18:00, 20:00–24:00 Jul 18 00:00–01:00, 15:00–17:00, 20:00–24:00 Jul 19 15:00–18:00, 20:00–24:00 Jul 20 16:00–20:00 Jul 21 00:00–01:00, 21:00–24:00 Jul 22 00:00–01:00, 18:00–24:00 Jul 23 18:00–22:00 Jul 24 00:00–02:00, 14:00–17:00, 20:00–24:00 Jul 25 00:00–02:00, 14:00–17:00, 20:00–22:00 Jul 26 16:00–17:00, 20:00–22:00 Jul 27 17:00–18:00