As per the S24 ending announcement thread…
We will be providing a Season 25 preview soon which will include the start time for the next season. Stay Tuned!
So, you’ll know as soon as everyone else does, i.e. when you see blue stickied in General Discussion. As S24 ends on 5th December, if they intend on starting S25 on 10th December, that would mean they’d have to patch 2.7.2 to live on Tuesday, 7th December, so the announcement of final patch notes would be prior to that.