Most often in May, 28 days.
Highest follower count seen that year: 667.
March
Mar 23 06:00–07:00, 12:00–19:00 Mar 24 02:00–08:00, 19:00–20:00, 22:00–24:00 Mar 25 00:00–02:00, 20:00–21:00 Mar 26 00:00–09:00 Mar 27 06:00–07:00, 09:00–10:00, 22:00–24:00 Mar 28 00:00–02:00, 04:00–05:00, 16:00–20:00, 22:00–24:00 Mar 29 00:00–02:00, 04:00–07:00, 10:00–11:00, 22:00–23:00 Mar 30 05:00–07:00, 09:00–15:00, 17:00–22:00 Mar 31 20:00–21:00, 23:00–24:00
April
Apr 1 00:00–07:00, 20:00–24:00 Apr 2 00:00–04:00, 06:00–07:00, 09:00–11:00 Apr 6 12:00–19:00 Apr 7 03:00–08:00, 10:00–16:00 Apr 8 07:00–08:00, 12:00–22:00 Apr 9 01:00–02:00, 06:00–17:00 Apr 10 00:00–18:00 Apr 11 05:00–06:00, 08:00–11:00, 17:00–22:00 Apr 12 02:00–03:00, 05:00–11:00, 13:00–14:00 Apr 13 01:00–18:00 Apr 14 13:00–20:00 Apr 16 06:00–21:00 Apr 17 12:00–13:00, 22:00–23:00 Apr 18 00:00–09:00, 20:00–24:00 Apr 19 00:00–01:00, 08:00–23:00 Apr 20 01:00–07:00 Apr 23 06:00–17:00 Apr 24 08:00–12:00, 22:00–24:00 Apr 25 16:00–20:00, 23:00–24:00 Apr 26 00:00–04:00, 06:00–11:00, 14:00–18:00 Apr 27 01:00–07:00, 19:00–20:00 Apr 28 01:00–18:00, 23:00–24:00 Apr 29 00:00–23:00 Apr 30 00:00–24:00
May
May 1 00:00–06:00, 20:00–23:00 May 2 01:00–04:00, 09:00–12:00, 19:00–20:00 May 3 06:00–07:00, 10:00–13:00, 23:00–24:00 May 4 00:00–02:00, 05:00–16:00 May 5 01:00–06:00, 18:00–20:00, 22:00–23:00 May 6 07:00–08:00 May 7 01:00–12:00, 18:00–21:00 May 8 07:00–11:00, 23:00–24:00 May 9 03:00–13:00, 16:00–20:00 May 10 02:00–03:00, 08:00–10:00, 12:00–19:00 May 11 02:00–07:00, 09:00–13:00, 22:00–23:00 May 12 02:00–17:00 May 13 03:00–09:00, 11:00–15:00 May 14 06:00–09:00, 14:00–23:00 May 15 02:00–06:00, 22:00–23:00 May 16 01:00–12:00 May 17 01:00–03:00, 06:00–10:00, 18:00–24:00 May 18 00:00–03:00, 06:00–12:00 May 19 07:00–08:00, 10:00–18:00, 20:00–21:00 May 21 01:00–03:00, 06:00–09:00, 11:00–13:00, 17:00–22:00 May 22 05:00–08:00, 13:00–19:00 May 24 02:00–04:00, 07:00–09:00, 12:00–16:00 May 26 02:00–06:00, 11:00–23:00 May 27 12:00–13:00, 22:00–24:00 May 28 20:00–24:00 May 29 00:00–02:00 May 30 05:00–08:00 May 31 16:00–19:00, 23:00–24:00
June
Jun 1 00:00–10:00 Jun 3 05:00–08:00 Jun 6 00:00–03:00 Jun 7 20:00–21:00 Jun 9 06:00–24:00 Jun 10 00:00–07:00, 09:00–15:00 Jun 11 16:00–21:00 Jun 12 12:00–20:00 Jun 13 09:00–11:00 Jun 15 01:00–12:00, 20:00–24:00 Jun 16 00:00–10:00, 14:00–24:00 Jun 18 08:00–09:00, 17:00–21:00 Jun 19 13:00–14:00, 18:00–19:00 Jun 20 07:00–08:00, 21:00–23:00 Jun 21 07:00–11:00 Jun 22 23:00–24:00 Jun 23 05:00–07:00, 23:00–24:00 Jun 25 16:00–17:00, 19:00–22:00 Jun 26 02:00–09:00 Jun 27 14:00–15:00