Most often in April, 30 days.
Highest follower count seen that year: 10,671.
January
Jan 3 16:00–17:00, 19:00–20:00 Jan 4 04:00–05:00, 09:00–14:00 Jan 5 03:00–05:00 Jan 6 00:00–01:00, 08:00–11:00, 17:00–18:00 Jan 7 09:00–12:00 Jan 8 09:00–11:00, 17:00–18:00 Jan 9 08:00–10:00, 17:00–18:00 Jan 10 09:00–11:00, 16:00–17:00 Jan 11 10:00–11:00, 18:00–20:00, 23:00–24:00 Jan 12 00:00–01:00, 08:00–10:00 Jan 13 03:00–10:00 Jan 14 09:00–11:00 Jan 15 02:00–03:00, 08:00–14:00, 16:00–17:00 Jan 17 08:00–10:00 Jan 18 03:00–05:00, 15:00–16:00 Jan 19 00:00–02:00, 09:00–10:00 Jan 20 06:00–08:00 Jan 21 07:00–08:00, 17:00–20:00, 23:00–24:00 Jan 22 00:00–02:00, 06:00–15:00 Jan 24 17:00–18:00 Jan 25 02:00–08:00 Jan 27 14:00–17:00 Jan 28 17:00–18:00 Jan 29 09:00–10:00, 17:00–18:00 Jan 31 16:00–18:00
February
Feb 1 03:00–04:00 Feb 2 12:00–19:00 Feb 4 08:00–09:00 Feb 5 03:00–06:00, 16:00–17:00 Feb 6 02:00–04:00 Feb 7 06:00–10:00, 13:00–14:00, 16:00–17:00 Feb 9 10:00–12:00, 20:00–22:00 Feb 11 08:00–13:00, 17:00–18:00 Feb 12 10:00–17:00 Feb 13 08:00–10:00 Feb 14 08:00–09:00, 22:00–23:00 Feb 16 08:00–09:00 Feb 18 10:00–12:00, 16:00–17:00 Feb 19 10:00–12:00, 16:00–17:00 Feb 20 08:00–09:00 Feb 21 11:00–14:00 Feb 24 01:00–03:00, 06:00–08:00, 16:00–17:00 Feb 26 10:00–11:00, 16:00–17:00 Feb 27 12:00–15:00
March
Mar 1 09:00–11:00, 21:00–22:00 Mar 2 09:00–10:00 Mar 3 07:00–10:00 Mar 4 09:00–10:00 Mar 5 07:00–09:00 Mar 9 05:00–07:00, 20:00–21:00 Mar 10 08:00–10:00 Mar 11 09:00–10:00 Mar 12 09:00–13:00 Mar 13 08:00–12:00, 23:00–24:00 Mar 14 07:00–09:00, 15:00–16:00 Mar 17 01:00–04:00, 07:00–08:00 Mar 18 06:00–07:00 Mar 19 06:00–11:00 Mar 20 08:00–09:00 Mar 21 07:00–08:00 Mar 22 09:00–11:00, 21:00–22:00 Mar 24 09:00–13:00 Mar 25 08:00–12:00 Mar 26 07:00–10:00 Mar 27 06:00–10:00 Mar 28 01:00–02:00, 07:00–09:00, 20:00–22:00 Mar 29 20:00–21:00 Mar 30 23:00–24:00 Mar 31 07:00–09:00
April
Apr 1 11:00–17:00, 19:00–20:00 Apr 2 01:00–03:00 Apr 3 09:00–17:00, 20:00–22:00 Apr 4 09:00–13:00, 15:00–17:00, 20:00–22:00 Apr 5 00:00–03:00, 06:00–08:00, 13:00–18:00 Apr 6 11:00–12:00 Apr 7 09:00–11:00, 15:00–17:00 Apr 8 09:00–12:00 Apr 9 02:00–03:00, 05:00–06:00, 15:00–16:00 Apr 10 07:00–09:00 Apr 11 08:00–10:00 Apr 12 08:00–11:00, 20:00–21:00 Apr 13 06:00–08:00, 17:00–19:00 Apr 14 15:00–16:00 Apr 15 08:00–12:00, 15:00–16:00 Apr 16 09:00–13:00, 15:00–16:00 Apr 17 10:00–12:00 Apr 18 16:00–17:00 Apr 19 02:00–03:00 Apr 20 19:00–20:00 Apr 21 06:00–08:00 Apr 22 14:00–15:00 Apr 23 06:00–08:00, 15:00–16:00 Apr 24 07:00–09:00, 14:00–15:00 Apr 25 07:00–09:00, 15:00–16:00 Apr 26 08:00–12:00 Apr 27 07:00–10:00 Apr 28 19:00–21:00 Apr 29 04:00–05:00 Apr 30 08:00–09:00
May
May 1 00:00–02:00, 16:00–17:00 May 2 09:00–11:00, 15:00–16:00 May 3 08:00–11:00 May 4 06:00–08:00, 11:00–13:00, 19:00–20:00 May 6 01:00–02:00, 11:00–16:00 May 7 16:00–17:00 May 8 19:00–20:00 May 9 08:00–09:00, 15:00–16:00 May 10 05:00–06:00 May 11 09:00–11:00, 21:00–23:00 May 15 12:00–13:00 May 16 19:00–20:00 May 17 10:00–17:00 May 20 01:00–02:00, 16:00–18:00 May 23 09:00–13:00 May 25 09:00–12:00, 19:00–21:00, 23:00–24:00 May 26 09:00–11:00 May 28 11:00–14:00 May 30 08:00–11:00
June
Jun 1 10:00–15:00, 17:00–24:00 Jun 2 00:00–05:00, 09:00–11:00, 18:00–20:00 Jun 3 20:00–22:00 Jun 5 00:00–01:00, 10:00–17:00 Jun 9 20:00–21:00 Jun 10 16:00–17:00 Jun 12 09:00–12:00 Jun 14 22:00–23:00 Jun 16 12:00–17:00, 19:00–20:00 Jun 20 21:00–23:00 Jun 21 00:00–02:00, 10:00–14:00 Jun 22 09:00–10:00 Jun 23 12:00–17:00 Jun 26 04:00–09:00 Jun 27 02:00–03:00, 13:00–14:00, 17:00–18:00 Jun 28 20:00–21:00 Jun 29 10:00–13:00 Jun 30 00:00–01:00
July
Jul 1 09:00–11:00, 15:00–16:00 Jul 2 06:00–08:00, 22:00–23:00 Jul 3 23:00–24:00 Jul 4 10:00–12:00, 14:00–16:00 Jul 7 02:00–03:00, 11:00–17:00 Jul 8 21:00–22:00 Jul 9 08:00–10:00, 21:00–22:00 Jul 10 07:00–10:00 Jul 11 10:00–13:00 Jul 12 14:00–17:00 Jul 13 12:00–13:00, 16:00–19:00 Jul 14 21:00–22:00 Jul 15 01:00–02:00, 10:00–14:00, 20:00–21:00 Jul 16 22:00–23:00 Jul 17 08:00–09:00, 21:00–23:00 Jul 18 10:00–15:00, 20:00–21:00 Jul 20 08:00–12:00, 20:00–22:00 Jul 21 11:00–13:00, 20:00–23:00 Jul 22 09:00–11:00 Jul 23 08:00–10:00, 14:00–15:00 Jul 24 00:00–01:00 Jul 25 08:00–10:00 Jul 26 10:00–11:00, 15:00–18:00, 23:00–24:00 Jul 28 09:00–12:00, 16:00–17:00 Jul 29 10:00–11:00, 21:00–22:00 Jul 30 13:00–16:00
August
Aug 2 11:00–18:00, 22:00–23:00 Aug 4 12:00–14:00, 20:00–22:00 Aug 5 08:00–10:00, 13:00–15:00 Aug 7 10:00–15:00, 21:00–22:00 Aug 9 08:00–12:00, 15:00–17:00 Aug 11 21:00–22:00 Aug 12 01:00–02:00, 11:00–14:00 Aug 14 09:00–10:00 Aug 15 00:00–01:00, 10:00–11:00 Aug 17 09:00–10:00 Aug 19 09:00–17:00, 19:00–20:00 Aug 24 07:00–08:00 Aug 28 10:00–12:00, 15:00–16:00 Aug 30 01:00–02:00 Aug 31 22:00–24:00
September
Sep 1 22:00–23:00 Sep 2 08:00–10:00 Sep 7 09:00–12:00 Sep 8 06:00–10:00, 15:00–16:00 Sep 10 07:00–08:00, 10:00–11:00 Sep 12 15:00–16:00, 19:00–20:00 Sep 13 10:00–11:00 Sep 15 08:00–11:00, 15:00–16:00 Sep 18 09:00–11:00 Sep 19 11:00–12:00 Sep 20 20:00–21:00 Sep 21 00:00–01:00 Sep 22 17:00–18:00 Sep 23 10:00–14:00 Sep 26 22:00–23:00 Sep 27 09:00–11:00 Sep 29 03:00–04:00, 07:00–08:00 Sep 30 12:00–16:00
October
Oct 1 09:00–11:00 Oct 7 01:00–02:00, 09:00–12:00 Oct 10 10:00–17:00 Oct 12 13:00–18:00 Oct 14 11:00–14:00 Oct 15 16:00–17:00 Oct 16 08:00–11:00, 16:00–17:00 Oct 17 12:00–15:00 Oct 25 08:00–11:00 Oct 28 14:00–15:00 Oct 30 07:00–08:00, 10:00–12:00
November
Nov 2 11:00–12:00, 17:00–18:00 Nov 3 14:00–16:00 Nov 6 08:00–09:00, 16:00–17:00 Nov 9 09:00–10:00, 17:00–18:00 Nov 10 16:00–17:00 Nov 11 02:00–03:00, 17:00–18:00 Nov 12 03:00–04:00, 06:00–11:00 Nov 13 17:00–18:00 Nov 14 16:00–17:00 Nov 15 08:00–09:00, 11:00–12:00, 17:00–18:00 Nov 17 00:00–02:00, 10:00–14:00 Nov 18 08:00–10:00, 13:00–14:00 Nov 19 16:00–17:00 Nov 20 06:00–17:00 Nov 21 11:00–16:00 Nov 24 03:00–05:00, 08:00–09:00 Nov 25 13:00–15:00 Nov 26 07:00–08:00, 22:00–23:00 Nov 28 01:00–02:00, 09:00–10:00, 12:00–14:00 Nov 29 00:00–01:00, 13:00–14:00
December
Dec 2 08:00–10:00, 17:00–18:00 Dec 3 08:00–09:00 Dec 4 09:00–10:00, 16:00–17:00 Dec 6 13:00–14:00, 18:00–20:00 Dec 8 10:00–15:00 Dec 9 16:00–17:00, 20:00–22:00 Dec 11 14:00–17:00 Dec 13 07:00–08:00, 14:00–15:00 Dec 15 05:00–06:00, 12:00–14:00, 17:00–18:00 Dec 16 16:00–17:00 Dec 18 17:00–18:00 Dec 21 07:00–09:00 Dec 22 04:00–05:00 Dec 23 11:00–13:00, 15:00–16:00 Dec 24 22:00–23:00 Dec 26 12:00–13:00 Dec 27 20:00–21:00 Dec 29 12:00–16:00 Dec 30 16:00–18:00 Dec 31 03:00–04:00, 08:00–09:00