Don't Pre-Order If You Can't Handle Problems
If you can't handle dealing with the problems that typically plague game's of this magnitude (24-player dog fights, 40-player multiplayer battles, the fact that this is a DICE game), you might want to hold off on putting in a pre-order.
DICE's engineers will do all that they can to put out a perfect product. That said, bugs and issues will slip through the cracks. They always do.
We don't expect Battlefront 2 to be a total disaster but it's going to be a huge, ambitious game with tons of moving parts and games of this size are always riddled with issues at launch. Beta or not.
If you're unwilling to deal with the initial batch of Star Wars Battlefront 2 problems and bugs, you might want to put in an order sometime after the game's release in November.
The developer will undoubtedly issue some quick updates to fix major problems, tweak weapons and classes, and add polish to the game.
The first update should arrive on day one (developers love to release day one patches) with another update a few weeks after release.