Most often in December, 31 days.
Highest follower count seen that year: 25,618.
August
Aug 8 23:00–24:00 Aug 9 00:00–05:00, 11:00–14:00, 22:00–24:00 Aug 10 00:00–05:00, 10:00–12:00, 22:00–24:00 Aug 11 00:00–02:00, 10:00–14:00, 22:00–24:00 Aug 12 00:00–01:00, 23:00–24:00 Aug 13 00:00–04:00, 10:00–11:00, 23:00–24:00 Aug 14 00:00–04:00, 10:00–13:00, 23:00–24:00 Aug 15 00:00–03:00, 10:00–12:00, 22:00–24:00 Aug 16 00:00–03:00, 05:00–13:00, 23:00–24:00 Aug 17 00:00–04:00, 22:00–24:00 Aug 18 00:00–01:00, 21:00–24:00 Aug 19 00:00–01:00, 22:00–24:00 Aug 20 00:00–03:00, 22:00–24:00 Aug 21 00:00–04:00, 13:00–14:00 Aug 22 00:00–02:00, 04:00–07:00, 10:00–12:00, 22:00–24:00 Aug 23 00:00–03:00, 10:00–13:00, 22:00–24:00 Aug 24 00:00–08:00, 22:00–24:00 Aug 25 01:00–03:00, 13:00–14:00, 21:00–24:00 Aug 26 02:00–04:00, 21:00–24:00 Aug 27 02:00–04:00 Aug 28 00:00–03:00, 20:00–24:00 Aug 29 02:00–04:00, 10:00–12:00, 21:00–24:00 Aug 30 00:00–03:00, 21:00–24:00 Aug 31 01:00–05:00, 23:00–24:00
September
Sep 1 00:00–02:00, 22:00–24:00 Sep 2 00:00–03:00, 11:00–13:00, 22:00–24:00 Sep 3 00:00–03:00, 21:00–24:00 Sep 4 00:00–01:00, 22:00–24:00 Sep 5 02:00–05:00, 10:00–12:00, 23:00–24:00 Sep 6 00:00–03:00, 05:00–06:00, 22:00–24:00 Sep 7 00:00–04:00, 11:00–12:00, 20:00–24:00 Sep 8 00:00–01:00, 10:00–11:00, 21:00–24:00 Sep 9 00:00–04:00 Sep 10 01:00–04:00, 23:00–24:00 Sep 11 00:00–01:00, 22:00–24:00 Sep 12 00:00–03:00, 10:00–12:00 Sep 13 00:00–03:00, 06:00–10:00, 23:00–24:00 Sep 14 00:00–04:00, 11:00–13:00, 22:00–24:00 Sep 15 00:00–03:00, 23:00–24:00 Sep 16 00:00–01:00, 10:00–13:00, 23:00–24:00 Sep 17 00:00–01:00, 07:00–08:00, 20:00–24:00 Sep 18 07:00–08:00, 10:00–12:00, 23:00–24:00 Sep 19 00:00–04:00, 08:00–12:00, 22:00–24:00 Sep 20 00:00–01:00, 03:00–08:00, 23:00–24:00 Sep 21 00:00–08:00, 22:00–24:00 Sep 22 00:00–03:00, 21:00–24:00 Sep 23 00:00–02:00, 07:00–10:00, 21:00–23:00 Sep 24 22:00–24:00 Sep 25 00:00–05:00, 21:00–24:00 Sep 26 00:00–03:00, 22:00–24:00 Sep 27 00:00–03:00, 07:00–09:00, 22:00–24:00 Sep 28 00:00–04:00, 06:00–09:00, 11:00–12:00, 21:00–23:00 Sep 29 22:00–24:00 Sep 30 00:00–02:00, 10:00–13:00, 23:00–24:00
October
Oct 1 00:00–04:00, 22:00–24:00 Oct 2 00:00–03:00, 23:00–24:00 Oct 3 00:00–03:00, 22:00–24:00 Oct 4 00:00–04:00, 23:00–24:00 Oct 5 01:00–05:00, 08:00–09:00, 22:00–24:00 Oct 6 00:00–03:00, 23:00–24:00 Oct 7 00:00–04:00 Oct 8 00:00–03:00, 09:00–10:00, 21:00–23:00 Oct 9 02:00–03:00, 23:00–24:00 Oct 10 00:00–02:00, 09:00–10:00, 23:00–24:00 Oct 11 00:00–03:00, 05:00–07:00, 10:00–12:00, 22:00–24:00 Oct 12 00:00–03:00, 13:00–14:00, 23:00–24:00 Oct 13 00:00–03:00, 22:00–24:00 Oct 14 00:00–03:00, 22:00–24:00 Oct 15 00:00–04:00, 22:00–24:00 Oct 16 00:00–03:00, 10:00–12:00, 22:00–24:00 Oct 17 00:00–01:00, 03:00–04:00, 23:00–24:00 Oct 18 00:00–03:00, 07:00–09:00, 22:00–24:00 Oct 19 00:00–03:00, 22:00–24:00 Oct 20 00:00–02:00 Oct 21 01:00–03:00, 07:00–11:00, 21:00–24:00 Oct 22 00:00–01:00, 22:00–24:00 Oct 23 00:00–01:00 Oct 24 23:00–24:00 Oct 25 00:00–02:00 Oct 26 00:00–02:00 Oct 28 00:00–04:00, 09:00–11:00, 22:00–24:00 Oct 29 00:00–02:00, 22:00–24:00 Oct 30 00:00–05:00, 09:00–12:00, 23:00–24:00 Oct 31 00:00–04:00, 23:00–24:00
November
Nov 1 00:00–04:00, 08:00–09:00, 23:00–24:00 Nov 2 00:00–03:00, 22:00–24:00 Nov 3 00:00–04:00, 09:00–11:00, 23:00–24:00 Nov 4 01:00–02:00, 10:00–11:00, 22:00–24:00 Nov 5 00:00–02:00, 08:00–11:00, 23:00–24:00 Nov 6 00:00–01:00, 04:00–05:00, 22:00–24:00 Nov 7 00:00–02:00, 09:00–11:00, 23:00–24:00 Nov 8 00:00–05:00, 23:00–24:00 Nov 9 00:00–04:00, 20:00–24:00 Nov 10 06:00–09:00, 23:00–24:00 Nov 11 00:00–02:00, 07:00–10:00, 23:00–24:00 Nov 12 00:00–03:00, 07:00–09:00, 23:00–24:00 Nov 13 00:00–02:00, 23:00–24:00 Nov 14 00:00–02:00, 23:00–24:00 Nov 15 00:00–03:00, 22:00–24:00 Nov 16 00:00–03:00, 22:00–24:00 Nov 17 00:00–02:00, 05:00–10:00, 22:00–24:00 Nov 18 00:00–03:00, 09:00–10:00, 22:00–24:00 Nov 19 00:00–03:00, 22:00–24:00 Nov 20 00:00–04:00, 08:00–09:00 Nov 21 00:00–03:00 Nov 22 01:00–04:00 Nov 23 23:00–24:00 Nov 24 00:00–01:00, 06:00–11:00, 23:00–24:00 Nov 25 00:00–03:00, 09:00–10:00, 22:00–24:00 Nov 26 00:00–03:00, 07:00–09:00 Nov 27 00:00–03:00, 07:00–08:00, 23:00–24:00 Nov 28 00:00–04:00 Nov 29 00:00–03:00, 05:00–06:00 Nov 30 00:00–04:00, 23:00–24:00
December
Dec 1 00:00–04:00, 21:00–24:00 Dec 2 00:00–03:00, 09:00–10:00 Dec 3 00:00–05:00, 22:00–24:00 Dec 4 00:00–07:00 Dec 5 00:00–02:00, 23:00–24:00 Dec 6 00:00–04:00, 23:00–24:00 Dec 7 00:00–05:00, 22:00–24:00 Dec 8 00:00–04:00, 23:00–24:00 Dec 9 00:00–03:00, 09:00–12:00, 22:00–24:00 Dec 10 00:00–03:00, 22:00–24:00 Dec 11 00:00–02:00, 09:00–11:00, 21:00–24:00 Dec 12 03:00–05:00, 09:00–11:00, 23:00–24:00 Dec 13 00:00–04:00, 09:00–11:00, 22:00–24:00 Dec 14 01:00–04:00 Dec 15 00:00–05:00, 23:00–24:00 Dec 16 00:00–04:00, 07:00–10:00, 23:00–24:00 Dec 17 00:00–03:00, 22:00–24:00 Dec 18 00:00–03:00, 23:00–24:00 Dec 19 00:00–05:00 Dec 20 00:00–03:00, 23:00–24:00 Dec 21 00:00–03:00, 22:00–23:00 Dec 22 00:00–04:00, 22:00–24:00 Dec 23 00:00–04:00, 09:00–10:00 Dec 24 03:00–07:00, 22:00–24:00 Dec 25 00:00–04:00, 22:00–24:00 Dec 26 00:00–03:00, 22:00–24:00 Dec 27 00:00–03:00, 09:00–10:00, 23:00–24:00 Dec 28 00:00–03:00, 22:00–24:00 Dec 29 00:00–04:00, 23:00–24:00 Dec 30 00:00–05:00, 07:00–09:00 Dec 31 00:00–05:00, 07:00–08:00, 23:00–24:00