H.J.
Give it a few weeks and be firm. Very firm don't give in it took both of our kids about 2 weeks to get use to the new idea. Something new and fun...but it didn't take long for them to realize that bedtime was still bedtime. The best advice is lay down the law now and stick to it until he realizes you mean business. We also have never had toys in the kids room while doing the transition which I think helped out a lot.