[dragonslayer]

it's easy to try without ai, just click on ai button so the man in bottom right corner doesn't have lit eyes.

as for xp, yes, it's wiser, xp wise to do in chapter 4. Because the xp you get in BS is a set amount it won't be affected by what your lvls are, but you'll get much more xp from monsters in chapters 2-4 if you don't finish BS until just before exiting chap. 4