Quick remind (US dates):
9th August 2016 - start of Legion content: Broken Shore, Demon Hunter, invasions (actual levelling experience was kinda "timegated" like class mount scenarios)
(77 days later) 25th October - 7.1
(77 days later) 10th January - 7.1.5
(77 days later) 28th March - 7.2
(77 days later) 13th June - 7.2.5
Predicted:
29th August - 7.3
14th November - 7.3.5
30th January - ???? (maybe even nothing or just PVP season 7)