Yes, stay up all night watching for it. Don't blink, you might miss it. No, really, once he is there he will be trapped. Assuming, of course, that you inverted the top of the bottle (you didn't answer that question).
Yeah, stick the beast in your refugium. Put a screen or something over your bulkhead. You don't want any chance for him to get in your display tank. They are great creatures to watch and extremely easy to care for. Mine is peering out of his rock right now watching me. I think he knows I'm talking about him.
Or you could give him to Jon and let him reap the benefits.