My DS has to go to bed by 7pm at the latest or we'll be looking at a 5:30-6am wake up. He's almost 18 months. I would love to be able to keep him up a little later for the sake of DH spending time with him in the evening and possibly get longer then an hour nap in the daytime (he currently averaging an hour nap). When could your LO start staying up a bit later without resulting in an early wake up?