If Square was smart they would release the jump potions [and set them to DT not EW start] and new characters 2-3 weeks before new expansion dropped.

People will be caught up ready to rumble on release.
They will have used 2-3 weeks of their monthly subscription and you can bait them into getting another month out of it.
You remove the frustration of catching up on release day.
You remove the multi queuing on launch when people have to log in, get the book, read the book, log out and log in again, repeating again if you want to change to another race. That's up to 3 10k+ queues these lads have to sit through.

But, what do I know.