Most often in March, 31 days.
Highest follower count seen that year: 3,418.
February
Feb 16 15:00–19:00, 21:00–24:00 UTC Feb 17 02:00–17:00 UTC Feb 18 01:00–04:00, 09:00–16:00, 18:00–19:00, 23:00–24:00 UTC Feb 19 03:00–08:00, 10:00–11:00, 13:00–20:00 UTC Feb 20 02:00–05:00, 08:00–09:00, 11:00–23:00 UTC Feb 21 02:00–07:00, 09:00–10:00, 12:00–21:00 UTC Feb 22 01:00–06:00, 08:00–09:00, 11:00–12:00, 14:00–22:00 UTC Feb 23 00:00–01:00, 05:00–09:00, 11:00–12:00, 16:00–17:00, 19:00–20:00, 22:00–24:00 UTC Feb 24 02:00–13:00, 16:00–19:00, 23:00–24:00 UTC Feb 25 00:00–04:00, 07:00–09:00, 14:00–21:00 UTC Feb 26 00:00–09:00, 12:00–15:00, 18:00–19:00 UTC Feb 27 02:00–08:00, 10:00–16:00, 18:00–21:00, 23:00–24:00 UTC Feb 28 04:00–07:00, 10:00–13:00, 16:00–21:00 UTC
March
Mar 1 02:00–03:00, 07:00–10:00, 14:00–20:00 UTC Mar 2 00:00–08:00, 11:00–19:00, 23:00–24:00 UTC Mar 3 00:00–01:00, 03:00–05:00, 08:00–09:00, 23:00–24:00 UTC Mar 4 00:00–01:00, 04:00–06:00, 08:00–10:00, 14:00–18:00, 20:00–21:00 UTC Mar 5 03:00–04:00, 17:00–19:00 UTC Mar 6 00:00–02:00, 11:00–14:00, 17:00–20:00 UTC Mar 7 05:00–21:00 UTC Mar 8 00:00–01:00, 04:00–06:00, 08:00–21:00 UTC Mar 9 01:00–02:00, 16:00–24:00 UTC Mar 10 03:00–05:00, 13:00–21:00, 23:00–24:00 UTC Mar 11 00:00–02:00, 04:00–16:00, 19:00–22:00 UTC Mar 12 00:00–11:00, 13:00–17:00, 19:00–22:00 UTC Mar 13 03:00–07:00, 18:00–19:00, 22:00–24:00 UTC Mar 14 03:00–06:00, 11:00–16:00, 19:00–21:00 UTC Mar 15 03:00–04:00, 06:00–07:00, 09:00–10:00 UTC Mar 16 00:00–04:00 UTC Mar 17 17:00–18:00 UTC Mar 18 00:00–06:00, 09:00–16:00, 22:00–24:00 UTC Mar 19 00:00–02:00, 04:00–07:00, 11:00–12:00, 14:00–20:00 UTC Mar 20 01:00–07:00, 12:00–14:00, 16:00–21:00 UTC Mar 21 02:00–07:00, 12:00–18:00, 22:00–24:00 UTC Mar 22 00:00–02:00, 05:00–08:00, 11:00–14:00, 17:00–23:00 UTC Mar 23 02:00–08:00, 20:00–21:00 UTC Mar 24 00:00–01:00, 04:00–11:00 UTC Mar 25 01:00–02:00, 12:00–16:00, 18:00–19:00, 23:00–24:00 UTC Mar 26 00:00–02:00, 05:00–07:00, 12:00–16:00 UTC Mar 27 04:00–05:00, 07:00–08:00, 10:00–12:00, 15:00–19:00 UTC Mar 28 04:00–07:00, 12:00–13:00, 22:00–24:00 UTC Mar 29 00:00–03:00, 08:00–10:00, 13:00–18:00 UTC Mar 30 08:00–12:00, 17:00–20:00 UTC Mar 31 00:00–03:00, 07:00–08:00 UTC
April
Apr 1 10:00–14:00, 16:00–17:00, 19:00–20:00 UTC Apr 2 04:00–14:00, 17:00–24:00 UTC Apr 3 04:00–07:00, 11:00–14:00 UTC Apr 4 04:00–06:00, 11:00–22:00 UTC Apr 5 04:00–10:00 UTC Apr 6 13:00–18:00 UTC Apr 7 03:00–07:00, 10:00–12:00, 16:00–18:00, 23:00–24:00 UTC Apr 8 00:00–07:00, 11:00–17:00 UTC Apr 9 01:00–08:00, 10:00–13:00, 15:00–16:00 UTC Apr 10 00:00–02:00, 06:00–07:00, 09:00–14:00, 18:00–20:00 UTC Apr 11 03:00–07:00, 16:00–19:00, 22:00–24:00 UTC Apr 12 00:00–01:00, 05:00–12:00, 14:00–15:00, 18:00–19:00 UTC Apr 13 03:00–08:00, 10:00–13:00, 15:00–16:00, 21:00–24:00 UTC Apr 14 00:00–01:00, 09:00–13:00, 16:00–17:00 UTC Apr 15 03:00–05:00, 08:00–09:00, 13:00–15:00 UTC Apr 16 03:00–08:00, 12:00–13:00, 15:00–18:00 UTC Apr 17 02:00–05:00, 10:00–11:00, 17:00–19:00 UTC Apr 18 02:00–04:00, 13:00–15:00, 18:00–19:00 UTC Apr 19 05:00–12:00 UTC Apr 20 18:00–22:00 UTC Apr 21 04:00–11:00, 18:00–19:00 UTC Apr 22 01:00–07:00, 11:00–12:00 UTC Apr 23 09:00–13:00, 17:00–24:00 UTC Apr 24 23:00–24:00 UTC Apr 25 00:00–02:00, 06:00–09:00, 11:00–16:00, 18:00–22:00 UTC Apr 26 04:00–05:00, 09:00–10:00, 12:00–13:00, 17:00–21:00 UTC Apr 27 04:00–08:00, 18:00–23:00 UTC Apr 28 04:00–11:00, 13:00–20:00, 22:00–23:00 UTC Apr 29 01:00–02:00, 07:00–13:00, 16:00–18:00, 21:00–23:00 UTC Apr 30 04:00–05:00, 07:00–09:00 UTC
May
May 1 01:00–06:00, 13:00–16:00 UTC May 2 08:00–14:00 UTC May 3 04:00–09:00, 11:00–14:00, 17:00–19:00 UTC May 4 05:00–07:00, 09:00–15:00, 17:00–20:00 UTC May 5 02:00–05:00, 09:00–12:00, 14:00–21:00, 23:00–24:00 UTC May 6 00:00–07:00, 09:00–13:00, 16:00–19:00, 22:00–24:00 UTC May 7 05:00–09:00, 11:00–13:00, 16:00–21:00 UTC May 8 06:00–08:00, 10:00–13:00, 17:00–24:00 UTC May 9 03:00–08:00, 12:00–17:00 UTC May 10 03:00–09:00, 11:00–13:00 UTC May 11 01:00–04:00, 08:00–15:00, 17:00–19:00, 22:00–24:00 UTC May 12 01:00–02:00, 04:00–08:00, 12:00–20:00 UTC May 13 05:00–11:00, 16:00–17:00, 20:00–24:00 UTC May 14 09:00–10:00, 16:00–18:00, 22:00–24:00 UTC May 15 00:00–06:00, 08:00–09:00, 12:00–18:00, 22:00–23:00 UTC May 16 00:00–01:00, 09:00–12:00, 16:00–22:00 UTC May 17 08:00–15:00 UTC May 18 11:00–15:00, 18:00–19:00 UTC May 19 04:00–06:00, 10:00–14:00 UTC May 20 10:00–12:00, 18:00–19:00 UTC May 21 02:00–11:00 UTC
June
Jun 12 15:00–20:00 UTC Jun 13 11:00–12:00 UTC Jun 15 11:00–14:00 UTC
July
Jul 4 09:00–15:00, 17:00–24:00 UTC Jul 5 03:00–21:00 UTC Jul 6 00:00–02:00, 04:00–13:00, 18:00–20:00 UTC Jul 7 00:00–12:00, 16:00–17:00, 21:00–24:00 UTC Jul 8 04:00–08:00, 10:00–12:00, 14:00–16:00, 20:00–24:00 UTC Jul 9 01:00–02:00, 10:00–17:00, 22:00–24:00 UTC Jul 10 00:00–03:00, 05:00–08:00, 10:00–16:00, 23:00–24:00 UTC Jul 11 00:00–03:00, 06:00–11:00, 13:00–18:00, 20:00–23:00 UTC Jul 12 04:00–06:00, 08:00–20:00 UTC Jul 13 01:00–03:00, 08:00–13:00 UTC Jul 14 00:00–01:00, 05:00–17:00 UTC Jul 15 00:00–02:00, 05:00–06:00, 12:00–16:00, 23:00–24:00 UTC Jul 16 00:00–01:00, 05:00–08:00, 11:00–13:00, 17:00–22:00 UTC Jul 17 04:00–05:00, 14:00–15:00, 18:00–21:00 UTC Jul 18 06:00–15:00 UTC Jul 19 00:00–03:00, 05:00–09:00, 11:00–13:00, 15:00–21:00 UTC Jul 20 04:00–08:00, 12:00–13:00, 18:00–24:00 UTC Jul 21 00:00–03:00, 13:00–14:00, 18:00–21:00 UTC Jul 22 05:00–06:00, 09:00–15:00, 17:00–22:00 UTC Jul 23 03:00–07:00, 10:00–18:00 UTC Jul 24 00:00–01:00 UTC Jul 25 11:00–12:00, 16:00–17:00, 20:00–21:00 UTC Jul 26 08:00–09:00, 13:00–14:00, 17:00–18:00, 19:00–22:00 UTC Jul 27 13:00–14:00, 20:00–21:00 UTC