Just be patient and keep offering. It's too soon, imo, to start thinking about assist feeding. If they hatched with good size and absorbed all the yolk prior to crawling out they can go quite a bit without eating. I have a baby that hatched out on 07/15 and has had one meal...a hopper mouse assist fed. That's it. Many assist attempts but he spits them out every time, no matter how far down I get the rat. Now that's stubborn...
Post up pics of the babies if you can. That will help determine how they're doing and if anything drastic needs to be done...although I doubt it...
Good luck with them...