So I haven't been seeing him long but we have this incredible connection. He saw his ex last Sunday and has been weird ever since, telling me he's busy but still reaching out consistently. He leaves to go out of town next weekend. How do I see him before then?
Nail him down for the next date

Your goal is to get a date with him before he goes to Vegas. Looks like you've agreed on a possible date on Wednesday and probably for only a short period of time. Not the best situation to be in, but he's not giving you much to work with.
I'm also a bit confused about your ultimate goal with him. If he just started acting weird after meeting his ex and he's going to vegas in a week, he doesn't sound like someone looking for a relationship. Maybe you just want to hook up?