Most often in August, 30 days.
Highest follower count seen that year: 17,870.
July
Jul 25 01:00–03:00, 09:00–14:00, 21:00–22:00 Jul 26 00:00–06:00, 08:00–09:00 Jul 27 00:00–05:00, 21:00–24:00 Jul 28 00:00–05:00, 07:00–10:00, 23:00–24:00 Jul 29 00:00–09:00, 23:00–24:00 Jul 30 01:00–03:00, 06:00–07:00 Jul 31 00:00–04:00, 06:00–11:00
August
Aug 1 00:00–05:00, 09:00–11:00 Aug 2 00:00–05:00, 08:00–10:00 Aug 3 09:00–11:00 Aug 4 23:00–24:00 Aug 6 06:00–11:00, 22:00–24:00 Aug 7 00:00–03:00, 05:00–08:00 Aug 8 00:00–03:00, 15:00–17:00 Aug 9 02:00–06:00, 08:00–10:00, 22:00–24:00 Aug 10 00:00–05:00, 08:00–10:00, 22:00–24:00 Aug 11 00:00–07:00, 09:00–13:00 Aug 12 01:00–04:00 Aug 13 09:00–12:00, 21:00–24:00 Aug 14 00:00–06:00 Aug 15 00:00–03:00, 08:00–11:00, 21:00–24:00 Aug 16 01:00–04:00, 07:00–09:00 Aug 17 02:00–10:00, 23:00–24:00 Aug 18 00:00–05:00, 12:00–13:00, 21:00–24:00 Aug 19 00:00–04:00, 07:00–08:00 Aug 20 05:00–09:00, 22:00–24:00 Aug 21 00:00–03:00, 21:00–24:00 Aug 22 00:00–04:00, 07:00–09:00, 11:00–12:00, 20:00–24:00 Aug 23 00:00–01:00, 08:00–11:00, 23:00–24:00 Aug 24 00:00–04:00, 19:00–24:00 Aug 25 00:00–01:00, 08:00–09:00 Aug 26 00:00–04:00, 07:00–08:00, 20:00–24:00 Aug 27 00:00–01:00, 03:00–05:00, 23:00–24:00 Aug 28 00:00–04:00, 08:00–12:00, 20:00–23:00 Aug 29 02:00–03:00, 09:00–10:00, 22:00–24:00 Aug 30 00:00–02:00, 08:00–09:00, 23:00–24:00 Aug 31 00:00–01:00, 03:00–04:00, 06:00–08:00
September
Sep 1 02:00–03:00 Sep 2 07:00–10:00, 12:00–14:00, 23:00–24:00 Sep 3 00:00–02:00, 06:00–08:00 Sep 4 01:00–10:00, 23:00–24:00 Sep 5 00:00–07:00 Sep 6 00:00–06:00, 22:00–24:00 Sep 7 01:00–02:00 Sep 8 23:00–24:00 Sep 9 00:00–03:00, 10:00–13:00, 22:00–24:00 Sep 10 00:00–02:00 Sep 11 06:00–09:00, 22:00–23:00 Sep 12 05:00–07:00, 16:00–17:00 Sep 13 00:00–03:00, 07:00–11:00 Sep 14 00:00–04:00, 09:00–14:00 Sep 15 01:00–04:00, 08:00–09:00 Sep 16 01:00–04:00 Sep 17 01:00–06:00, 10:00–14:00 Sep 18 01:00–05:00 Sep 19 00:00–04:00, 22:00–24:00 Sep 20 00:00–01:00, 04:00–06:00 Sep 22 00:00–07:00, 10:00–13:00, 23:00–24:00 Sep 23 00:00–04:00 Sep 24 00:00–06:00 Sep 25 03:00–05:00, 08:00–11:00 Sep 26 01:00–03:00, 20:00–24:00 Sep 27 03:00–07:00, 11:00–13:00 Sep 28 01:00–07:00, 10:00–12:00 Sep 29 02:00–05:00, 10:00–12:00 Sep 30 01:00–05:00
October
Oct 1 23:00–24:00 Oct 2 00:00–07:00, 09:00–13:00 Oct 3 05:00–09:00 Oct 4 02:00–05:00, 23:00–24:00 Oct 5 00:00–03:00 Oct 7 00:00–03:00, 07:00–09:00, 23:00–24:00 Oct 8 00:00–04:00, 06:00–08:00 Oct 9 00:00–03:00, 07:00–11:00, 22:00–24:00 Oct 10 00:00–04:00, 09:00–10:00 Oct 11 11:00–14:00, 23:00–24:00 Oct 12 00:00–02:00 Oct 13 03:00–05:00 Oct 14 00:00–03:00, 16:00–17:00 Oct 15 23:00–24:00 Oct 16 00:00–04:00, 08:00–10:00 Oct 17 02:00–09:00, 23:00–24:00 Oct 18 00:00–03:00, 05:00–07:00 Oct 19 20:00–24:00 Oct 20 01:00–02:00 Oct 21 00:00–04:00, 23:00–24:00 Oct 22 00:00–04:00, 08:00–11:00 Oct 23 02:00–06:00, 09:00–12:00 Oct 24 00:00–03:00, 05:00–07:00, 09:00–10:00 Oct 25 08:00–11:00 Oct 26 02:00–06:00, 09:00–10:00, 14:00–16:00 Oct 28 06:00–07:00, 10:00–12:00 Oct 30 02:00–08:00, 10:00–14:00 Oct 31 09:00–13:00
November
Nov 1 03:00–09:00 Nov 2 04:00–07:00 Nov 3 11:00–14:00 Nov 4 12:00–16:00 Nov 5 03:00–06:00 Nov 6 03:00–08:00, 12:00–13:00 Nov 7 04:00–07:00 Nov 8 09:00–15:00 Nov 9 03:00–08:00 Nov 12 01:00–04:00, 08:00–13:00 Nov 13 03:00–07:00, 23:00–24:00 Nov 14 00:00–02:00, 08:00–12:00 Nov 15 02:00–04:00, 08:00–10:00 Nov 16 03:00–05:00, 13:00–19:00 Nov 18 04:00–08:00, 15:00–18:00 Nov 19 03:00–07:00, 22:00–24:00 Nov 20 00:00–02:00, 04:00–08:00, 10:00–14:00 Nov 21 05:00–07:00, 09:00–14:00 Nov 22 11:00–15:00, 21:00–23:00 Nov 24 19:00–24:00 Nov 25 14:00–15:00 Nov 26 11:00–13:00, 23:00–24:00 Nov 27 01:00–07:00 Nov 28 00:00–05:00 Nov 29 11:00–15:00 Nov 30 01:00–05:00, 07:00–15:00, 21:00–24:00
December
Dec 1 00:00–05:00 Dec 2 01:00–04:00, 12:00–14:00 Dec 3 01:00–03:00, 09:00–13:00 Dec 4 03:00–09:00, 23:00–24:00 Dec 5 00:00–03:00, 08:00–13:00, 23:00–24:00 Dec 6 00:00–03:00, 09:00–14:00 Dec 7 03:00–05:00, 07:00–10:00, 16:00–17:00 Dec 8 02:00–04:00 Dec 9 00:00–02:00, 07:00–08:00, 14:00–15:00, 21:00–24:00 Dec 10 00:00–02:00 Dec 11 12:00–15:00 Dec 12 03:00–07:00, 12:00–15:00 Dec 13 03:00–05:00, 07:00–12:00, 21:00–23:00 Dec 14 00:00–02:00, 11:00–14:00, 21:00–24:00 Dec 15 00:00–02:00, 07:00–10:00, 19:00–24:00 Dec 16 04:00–05:00 Dec 17 02:00–04:00, 16:00–17:00 Dec 18 10:00–14:00, 20:00–22:00 Dec 20 02:00–05:00, 08:00–10:00, 12:00–13:00 Dec 21 01:00–04:00 Dec 22 12:00–17:00 Dec 23 01:00–05:00, 14:00–15:00 Dec 24 01:00–04:00 Dec 25 02:00–06:00 Dec 26 02:00–03:00 Dec 27 03:00–06:00, 09:00–11:00 Dec 28 03:00–09:00, 14:00–17:00 Dec 29 10:00–12:00 Dec 30 22:00–24:00 Dec 31 00:00–02:00