They probably won't die if they're in there for about a month as long as you try to keep them in a warm spot and change the water enough (don't go overboard) and stuff. Just don't stress a whole lot about it, there's not a lot you can do anyways at this point. And don't even think of getting the tank set up and thinking that it would be better for them in there while it's cycling...trust us when we say it wouldn't.
As for cycling, other than using establish gravel as a "seed", no, there really isn't a faster way and even that isn't a guarantee. You can put a danio in there but then you'd have to return him after your tank is done. Think of this as a realllly good lesson to do research and have all your stuff before you actually have the fish :) You're doing a good thing and providing a better home for the betta.