Most often in May, 31 days.
Highest follower count seen that year: 63,029.
January
Jan 1 18:00–20:00 Jan 2 18:00–21:00 Jan 3 14:00–16:00 Jan 4 19:00–22:00 Jan 5 15:00–18:00 Jan 6 18:00–21:00 Jan 7 14:00–17:00 Jan 8 18:00–22:00 Jan 9 14:00–17:00 Jan 10 14:00–17:00 Jan 11 23:00–24:00 Jan 12 00:00–01:00, 15:00–19:00 Jan 13 21:00–24:00 Jan 14 00:00–01:00, 22:00–24:00 Jan 15 00:00–01:00, 15:00–17:00 Jan 17 21:00–24:00 Jan 18 18:00–22:00 Jan 19 17:00–20:00 Jan 20 14:00–18:00 Jan 21 15:00–17:00 Jan 23 10:00–13:00 Jan 26 14:00–18:00 Jan 28 15:00–16:00 Jan 29 14:00–17:00 Jan 31 15:00–18:00
February
Feb 3 14:00–16:00 Feb 4 14:00–16:00 Feb 5 18:00–19:00 Feb 6 11:00–15:00 Feb 7 14:00–18:00 Feb 9 18:00–21:00 Feb 10 14:00–17:00 Feb 12 15:00–18:00 Feb 13 14:00–17:00 Feb 14 22:00–24:00 Feb 15 23:00–24:00 Feb 16 22:00–24:00 Feb 17 15:00–18:00 Feb 18 09:00–11:00, 14:00–17:00, 22:00–24:00 Feb 19 00:00–01:00, 21:00–24:00 Feb 20 15:00–16:00 Feb 21 15:00–18:00 Feb 22 22:00–24:00 Feb 23 00:00–01:00, 18:00–20:00 Feb 24 14:00–18:00 Feb 25 15:00–16:00, 22:00–23:00 Feb 26 15:00–17:00, 23:00–24:00 Feb 27 00:00–02:00, 14:00–17:00, 22:00–24:00 Feb 28 18:00–24:00
March
Mar 2 15:00–17:00 Mar 3 14:00–17:00, 23:00–24:00 Mar 4 00:00–01:00, 18:00–21:00 Mar 5 18:00–21:00 Mar 6 21:00–23:00 Mar 7 14:00–17:00, 23:00–24:00 Mar 8 00:00–02:00 Mar 9 20:00–24:00 Mar 10 14:00–17:00 Mar 11 14:00–17:00 Mar 12 15:00–16:00 Mar 13 14:00–16:00 Mar 14 18:00–22:00 Mar 15 14:00–17:00 Mar 16 18:00–21:00 Mar 18 22:00–24:00 Mar 19 00:00–01:00, 21:00–24:00 Mar 20 15:00–18:00, 22:00–24:00 Mar 22 18:00–20:00 Mar 23 17:00–24:00 Mar 24 00:00–01:00, 14:00–18:00 Mar 25 14:00–16:00 Mar 26 14:00–16:00, 22:00–24:00 Mar 27 00:00–01:00, 14:00–15:00 Mar 28 21:00–24:00 Mar 29 00:00–01:00, 18:00–23:00 Mar 30 20:00–24:00 Mar 31 14:00–15:00
April
Apr 1 13:00–17:00 Apr 2 14:00–17:00, 21:00–23:00 Apr 3 14:00–17:00 Apr 4 14:00–18:00, 20:00–21:00 Apr 5 22:00–24:00 Apr 6 17:00–19:00 Apr 7 13:00–14:00 Apr 8 22:00–24:00 Apr 9 13:00–16:00 Apr 10 14:00–17:00 Apr 15 14:00–17:00 Apr 17 20:00–22:00 Apr 20 16:00–18:00, 21:00–24:00 Apr 21 00:00–01:00, 18:00–20:00 Apr 23 14:00–17:00, 22:00–24:00 Apr 24 00:00–01:00, 18:00–20:00 Apr 25 17:00–21:00 Apr 26 18:00–20:00 Apr 27 14:00–16:00 Apr 29 20:00–24:00 Apr 30 17:00–21:00
May
May 1 17:00–20:00 May 2 20:00–22:00 May 3 21:00–24:00 May 4 17:00–21:00 May 5 14:00–16:00 May 6 21:00–24:00 May 7 00:00–01:00, 14:00–17:00 May 8 14:00–17:00 May 9 17:00–19:00 May 10 17:00–19:00 May 11 16:00–20:00 May 12 13:00–16:00 May 13 21:00–24:00 May 14 00:00–01:00, 21:00–24:00 May 15 14:00–16:00 May 16 18:00–21:00 May 17 21:00–24:00 May 18 20:00–23:00 May 19 14:00–17:00 May 20 17:00–20:00 May 21 20:00–24:00 May 22 14:00–17:00 May 23 21:00–23:00 May 24 20:00–23:00 May 25 20:00–23:00 May 26 14:00–17:00 May 27 14:00–17:00, 22:00–23:00 May 28 17:00–19:00, 21:00–22:00 May 29 14:00–16:00 May 30 21:00–24:00 May 31 00:00–01:00, 21:00–24:00
June
Jun 1 21:00–24:00 Jun 2 09:00–11:00, 13:00–17:00 Jun 3 14:00–16:00, 22:00–24:00 Jun 4 00:00–01:00, 21:00–24:00 Jun 5 00:00–01:00 Jun 10 22:00–24:00 Jun 11 00:00–01:00, 21:00–24:00 Jun 12 14:00–17:00 Jun 16 21:00–23:00 Jun 17 20:00–23:00 Jun 19 21:00–23:00 Jun 20 13:00–17:00 Jun 23 22:00–24:00 Jun 24 21:00–24:00 Jun 25 00:00–01:00, 16:00–19:00, 21:00–24:00 Jun 30 16:00–20:00
July
Jul 2 21:00–24:00 Jul 3 00:00–01:00, 20:00–22:00 Jul 4 20:00–23:00 Jul 5 14:00–16:00 Jul 7 22:00–24:00 Jul 8 21:00–24:00 Jul 9 22:00–24:00 Jul 10 22:00–24:00 Jul 12 17:00–20:00 Jul 13 20:00–24:00 Jul 14 21:00–23:00 Jul 15 22:00–23:00 Jul 16 14:00–17:00, 21:00–24:00 Jul 17 00:00–01:00, 14:00–15:00, 17:00–24:00 Jul 18 18:00–19:00, 21:00–24:00 Jul 19 00:00–02:00, 14:00–17:00 Jul 20 14:00–16:00 Jul 21 17:00–20:00 Jul 22 14:00–17:00, 21:00–24:00 Jul 23 22:00–24:00 Jul 24 00:00–01:00, 21:00–24:00 Jul 25 00:00–01:00, 17:00–20:00, 22:00–23:00 Jul 26 21:00–24:00 Jul 27 21:00–24:00 Jul 28 00:00–01:00, 21:00–24:00
August
Aug 3 21:00–24:00 Aug 4 16:00–19:00 Aug 5 21:00–24:00 Aug 6 17:00–20:00, 22:00–24:00 Aug 7 20:00–24:00 Aug 8 21:00–23:00 Aug 9 14:00–16:00 Aug 10 21:00–24:00 Aug 11 00:00–01:00 Aug 12 22:00–24:00 Aug 13 00:00–01:00, 22:00–24:00 Aug 14 20:00–22:00 Aug 15 21:00–24:00 Aug 17 14:00–17:00, 21:00–23:00 Aug 18 18:00–23:00 Aug 19 22:00–24:00 Aug 20 00:00–01:00, 14:00–17:00, 21:00–22:00 Aug 21 18:00–22:00 Aug 22 21:00–24:00 Aug 23 20:00–24:00 Aug 25 17:00–24:00 Aug 26 13:00–16:00, 23:00–24:00 Aug 27 18:00–24:00 Aug 28 17:00–22:00 Aug 29 14:00–18:00 Aug 31 20:00–24:00
September
Sep 1 20:00–22:00 Sep 2 21:00–24:00 Sep 3 16:00–22:00 Sep 4 21:00–23:00 Sep 5 17:00–19:00 Sep 7 14:00–18:00, 21:00–24:00 Sep 9 14:00–17:00, 21:00–23:00 Sep 10 14:00–17:00 Sep 11 17:00–21:00 Sep 12 22:00–24:00 Sep 13 00:00–01:00, 17:00–20:00 Sep 17 14:00–17:00 Sep 18 17:00–21:00 Sep 19 17:00–20:00 Sep 21 14:00–18:00 Sep 25 08:00–12:00 Sep 26 08:00–11:00 Sep 27 14:00–17:00 Sep 28 08:00–09:00 Sep 29 09:00–14:00 Sep 30 08:00–11:00
October
Oct 1 14:00–17:00 Oct 2 08:00–11:00, 13:00–15:00 Oct 3 14:00–16:00 Oct 4 17:00–20:00 Oct 5 14:00–17:00 Oct 6 14:00–16:00 Oct 7 14:00–17:00 Oct 9 15:00–18:00 Oct 16 21:00–24:00 Oct 17 15:00–17:00 Oct 18 21:00–24:00 Oct 19 14:00–17:00 Oct 20 14:00–17:00 Oct 22 21:00–24:00 Oct 27 15:00–18:00 Oct 28 15:00–18:00 Oct 29 18:00–20:00, 22:00–24:00 Oct 30 00:00–01:00, 14:00–16:00, 22:00–24:00
November
Nov 1 14:00–17:00, 22:00–24:00 Nov 2 00:00–02:00, 15:00–19:00 Nov 3 14:00–18:00 Nov 4 14:00–18:00 Nov 6 22:00–24:00 Nov 7 22:00–24:00 Nov 8 15:00–18:00 Nov 9 23:00–24:00 Nov 10 00:00–02:00, 15:00–17:00 Nov 13 22:00–24:00 Nov 14 00:00–01:00, 23:00–24:00 Nov 15 00:00–02:00, 21:00–24:00 Nov 16 00:00–01:00, 18:00–20:00 Nov 17 15:00–18:00 Nov 20 15:00–18:00 Nov 21 15:00–18:00, 23:00–24:00 Nov 22 00:00–01:00, 18:00–24:00 Nov 23 23:00–24:00 Nov 24 00:00–01:00, 15:00–17:00 Nov 25 15:00–16:00 Nov 26 18:00–24:00 Nov 27 14:00–15:00 Nov 29 11:00–13:00 Nov 30 22:00–24:00
December
Dec 1 00:00–02:00 Dec 2 18:00–19:00 Dec 3 18:00–20:00 Dec 4 18:00–22:00 Dec 5 19:00–21:00 Dec 6 15:00–20:00 Dec 7 21:00–24:00 Dec 8 00:00–01:00, 18:00–21:00 Dec 9 22:00–24:00 Dec 10 18:00–24:00 Dec 11 15:00–16:00 Dec 12 15:00–18:00, 22:00–24:00 Dec 14 15:00–19:00 Dec 15 14:00–17:00 Dec 16 15:00–18:00, 22:00–24:00 Dec 18 14:00–18:00 Dec 19 15:00–18:00 Dec 20 18:00–21:00 Dec 21 18:00–20:00 Dec 22 14:00–17:00 Dec 23 22:00–24:00 Dec 24 00:00–01:00, 15:00–17:00 Dec 25 18:00–21:00