Most often in March, 27 days.
Highest follower count seen that year: 258,383.
January
Jan 1 20:00–24:00 Jan 2 00:00–02:00 Jan 4 21:00–24:00 Jan 5 00:00–02:00, 21:00–24:00 Jan 6 00:00–01:00 Jan 7 21:00–24:00 Jan 8 00:00–02:00, 21:00–24:00 Jan 9 00:00–03:00, 21:00–22:00 Jan 11 20:00–24:00 Jan 12 00:00–01:00, 21:00–24:00 Jan 13 00:00–01:00, 21:00–24:00 Jan 14 00:00–01:00, 21:00–22:00 Jan 17 21:00–22:00 Jan 18 21:00–24:00 Jan 19 00:00–01:00, 21:00–24:00 Jan 20 00:00–01:00 Jan 22 21:00–24:00 Jan 23 00:00–02:00, 21:00–22:00 Jan 24 22:00–24:00 Jan 25 00:00–03:00, 21:00–24:00 Jan 26 00:00–02:00 Jan 28 22:00–24:00 Jan 29 00:00–01:00, 22:00–24:00 Jan 30 22:00–24:00 Jan 31 00:00–02:00, 22:00–24:00
February
Feb 1 00:00–01:00 Feb 4 21:00–24:00 Feb 5 00:00–03:00 Feb 8 22:00–24:00 Feb 9 00:00–02:00 Feb 10 22:00–24:00 Feb 11 00:00–03:00, 23:00–24:00 Feb 12 00:00–04:00 Feb 13 00:00–04:00, 23:00–24:00 Feb 14 00:00–02:00 Feb 16 00:00–05:00 Feb 17 23:00–24:00 Feb 18 00:00–03:00 Feb 19 23:00–24:00 Feb 20 00:00–02:00 Feb 21 23:00–24:00 Feb 22 00:00–04:00, 23:00–24:00 Feb 23 00:00–03:00, 22:00–24:00 Feb 24 00:00–02:00 Feb 27 00:00–02:00, 22:00–24:00 Feb 28 00:00–04:00, 23:00–24:00
March
Mar 1 00:00–03:00, 22:00–24:00 Mar 4 23:00–24:00 Mar 5 00:00–04:00 Mar 6 23:00–24:00 Mar 7 00:00–03:00, 23:00–24:00 Mar 8 00:00–02:00 Mar 9 23:00–24:00 Mar 10 00:00–04:00 Mar 12 00:00–01:00, 22:00–24:00 Mar 13 00:00–03:00 Mar 14 00:00–04:00, 22:00–24:00 Mar 15 00:00–02:00 Mar 16 22:00–24:00 Mar 17 00:00–03:00, 22:00–24:00 Mar 18 00:00–03:00, 22:00–24:00 Mar 19 00:00–04:00 Mar 21 00:00–04:00 Mar 22 22:00–24:00 Mar 23 00:00–02:00, 22:00–24:00 Mar 24 00:00–01:00 Mar 25 21:00–23:00 Mar 26 21:00–24:00 Mar 27 00:00–02:00 Mar 28 21:00–24:00 Mar 29 00:00–02:00 Mar 30 21:00–24:00 Mar 31 00:00–02:00
April
Apr 2 21:00–24:00 Apr 3 00:00–02:00 Apr 4 20:00–23:00 Apr 6 20:00–24:00 Apr 8 20:00–23:00 Apr 9 20:00–24:00 Apr 10 00:00–01:00, 20:00–23:00 Apr 12 21:00–24:00 Apr 13 20:00–24:00 Apr 14 00:00–01:00, 21:00–24:00 Apr 15 00:00–01:00, 20:00–24:00 Apr 16 00:00–01:00 Apr 17 20:00–24:00 Apr 19 20:00–24:00 Apr 20 00:00–01:00 Apr 21 20:00–24:00 Apr 22 20:00–24:00 Apr 23 20:00–24:00 Apr 24 00:00–01:00, 20:00–24:00 Apr 25 00:00–01:00 Apr 26 20:00–24:00 Apr 27 20:00–24:00 Apr 28 20:00–24:00 Apr 29 20:00–24:00 Apr 30 20:00–24:00
May
May 1 00:00–01:00 May 4 20:00–24:00 May 5 00:00–01:00 May 6 20:00–23:00 May 7 20:00–24:00 May 8 00:00–01:00, 20:00–24:00 May 9 00:00–01:00 May 10 20:00–24:00 May 11 00:00–01:00, 21:00–24:00 May 12 00:00–01:00, 21:00–24:00 May 13 00:00–01:00, 20:00–24:00 May 14 21:00–24:00 May 16 20:00–24:00 May 17 00:00–01:00, 20:00–24:00 May 18 00:00–01:00, 20:00–24:00 May 19 00:00–01:00 May 20 20:00–22:00 May 21 20:00–24:00 May 22 00:00–01:00 May 23 21:00–24:00 May 24 00:00–01:00, 20:00–23:00 May 26 20:00–24:00 May 27 00:00–01:00, 20:00–24:00 May 28 00:00–01:00, 21:00–24:00 May 29 00:00–01:00, 22:00–24:00 May 30 00:00–01:00
June
Jun 6 20:00–24:00 Jun 7 00:00–01:00, 20:00–22:00 Jun 8 20:00–24:00 Jun 9 00:00–01:00, 21:00–24:00 Jun 10 00:00–01:00, 20:00–24:00 Jun 11 00:00–01:00, 20:00–24:00 Jun 12 00:00–01:00, 21:00–24:00 Jun 13 00:00–01:00, 21:00–24:00 Jun 14 00:00–02:00, 20:00–24:00 Jun 18 21:00–24:00 Jun 19 00:00–01:00, 21:00–24:00 Jun 21 21:00–24:00 Jun 22 00:00–02:00, 21:00–24:00 Jun 23 00:00–02:00 Jun 25 21:00–24:00 Jun 26 00:00–02:00, 21:00–24:00 Jun 27 00:00–01:00, 21:00–24:00 Jun 28 00:00–03:00, 21:00–24:00
July
Jul 2 21:00–24:00 Jul 3 00:00–02:00, 21:00–24:00 Jul 4 00:00–02:00 Jul 6 21:00–24:00 Jul 7 00:00–01:00 Jul 9 21:00–24:00 Jul 10 00:00–02:00 Jul 11 21:00–24:00 Jul 12 00:00–01:00 Jul 13 22:00–24:00 Jul 14 00:00–01:00 Jul 16 21:00–24:00 Jul 18 21:00–24:00 Jul 19 00:00–01:00, 21:00–24:00 Jul 20 00:00–01:00 Jul 21 22:00–24:00 Jul 22 00:00–03:00 Jul 25 20:00–23:00 Jul 26 20:00–24:00 Jul 28 21:00–24:00 Jul 29 00:00–01:00, 22:00–24:00 Jul 30 00:00–02:00 Jul 31 21:00–24:00
August
Aug 1 00:00–02:00 Aug 3 22:00–24:00 Aug 4 00:00–02:00 Aug 5 21:00–24:00 Aug 6 21:00–24:00 Aug 7 00:00–01:00 Aug 10 21:00–24:00 Aug 11 00:00–02:00 Aug 12 22:00–24:00 Aug 13 00:00–02:00 Aug 15 21:00–24:00 Aug 16 00:00–01:00, 22:00–24:00 Aug 17 00:00–01:00 Aug 18 21:00–24:00 Aug 19 00:00–01:00 Aug 21 21:00–24:00 Aug 22 00:00–02:00 Aug 23 21:00–24:00 Aug 25 22:00–24:00 Aug 26 00:00–02:00 Aug 27 22:00–24:00 Aug 28 00:00–02:00 Aug 31 19:00–22:00
September
Sep 1 18:00–22:00 Sep 2 18:00–22:00 Sep 4 18:00–19:00 Sep 6 19:00–23:00 Sep 7 18:00–22:00 Sep 8 18:00–23:00 Sep 11 19:00–23:00 Sep 12 19:00–22:00 Sep 13 19:00–23:00 Sep 14 18:00–21:00 Sep 15 18:00–21:00 Sep 18 18:00–23:00 Sep 20 19:00–21:00 Sep 21 18:00–23:00 Sep 22 18:00–20:00 Sep 23 19:00–24:00 Sep 24 18:00–21:00 Sep 25 18:00–23:00 Sep 26 19:00–24:00 Sep 28 18:00–22:00 Sep 29 18:00–23:00 Sep 30 18:00–22:00
October
Oct 3 18:00–23:00 Oct 5 18:00–23:00 Oct 6 19:00–23:00 Oct 7 18:00–22:00 Oct 10 18:00–22:00 Oct 11 18:00–23:00 Oct 12 18:00–20:00 Oct 13 18:00–22:00 Oct 14 18:00–23:00 Oct 15 18:00–23:00 Oct 18 18:00–22:00 Oct 19 18:00–23:00 Oct 21 18:00–22:00 Oct 22 18:00–20:00 Oct 24 18:00–22:00 Oct 25 18:00–22:00 Oct 26 18:00–23:00 Oct 27 18:00–22:00 Oct 30 18:00–22:00 Oct 31 18:00–22:00
November
Nov 4 18:00–22:00 Nov 5 19:00–22:00 Nov 8 18:00–23:00 Nov 10 19:00–23:00 Nov 11 19:00–23:00 Nov 12 19:00–21:00 Nov 13 18:00–22:00 Nov 14 18:00–23:00 Nov 21 18:00–22:00 Nov 23 19:00–23:00 Nov 25 18:00–23:00 Nov 27 21:00–24:00 Nov 28 00:00–01:00, 22:00–24:00 Nov 29 21:00–24:00 Nov 30 00:00–02:00, 21:00–24:00
December
Dec 1 00:00–01:00 Dec 3 21:00–24:00 Dec 4 00:00–02:00, 21:00–24:00 Dec 5 00:00–01:00 Dec 6 21:00–24:00 Dec 7 00:00–01:00 Dec 9 18:00–22:00 Dec 10 18:00–22:00 Dec 11 18:00–22:00 Dec 13 18:00–23:00 Dec 14 17:00–22:00 Dec 15 17:00–22:00 Dec 18 18:00–22:00 Dec 20 17:00–22:00 Dec 23 17:00–21:00 Dec 25 17:00–21:00 Dec 26 17:00–20:00 Dec 28 17:00–21:00 Dec 29 17:00–20:00 Dec 30 17:00–22:00