Get 18 Month Old on a Schedule.

Honestly? He just sounds like an early riser right now. His body clock is telling him that no matter when he naps or goes to bed he MUST wake up at 5:30. It may be a phase and most likely is, but this could also just be how his body works. As he gets older you can explain the rules to him about playing quietly in his room because the rest of the people in the house need to sleep until [whatever time].

I would probably nurse him and give him a small snack to hold him until breakfast, like those cereal star puffs from Gerber. When he's done, put him back in his crib quietly. Don't talk during this whole time, don't turn on lights, just take care of business and go back to bed. Treat it like the middle of the night.

What happens if you go in at 5:30 am and just lay him back down?
No other response. Just go in in the dark, lay him back down and walk out?

I've done that with my DD, and she got the message after a few rounds of that that it's not time to wake up yet.

(DS is a different story, but every kid is different).
Just wondering if you've tried that.

Also, do you have any kind of crib soother in there? We have an aquarium that he can turn on and watch if he wakes up. You could turn that on when you go lay him down at 5:30, if he's not having it.

Just a thought. Not sure if you've already tried that...

I also feel your pain! My son, now 2 1/2, started waking around 5:30 just after his first birthday. He was in a crib in our room and no amount of back rubbing, singing, rocking, holding, anything, would get him back to sleep.
The first thing we had to overcome was the teething. Every single one of his teeth caused extreme discomfort and a bad cold. It was such a pain, but after all those big teeth finally came in we moved him into his sister's room (only a 2 bedroom house) where he slept slightly better but would still wake most mornings at an unreasonable hour.
We tried sleep training a few times (didn't work), earlier to bed, shorter nap, nothing made a difference. In the end, we would bring him into our room when he woke so he wouldn't wake his sister, and I would nurse him and on the lucky mornings when he fell back asleep I'd carefully slide down into bed with him and he'd sleep on my chest.
I never thought I'd be so accommodating to a young child for the long term! But, damn, waking up at 5:30 sucks. My husband and I still trade sleeping in a little every other morning and while it hasn't been great for our marriage, it gets us through and it's getting better. You have to come up with some compromise that works for your family. I keep telling myself he won't be doing this when he's 4 or 5.
Nowadays, he feels his nap is "optional" and so we have a different set of problems. He wakes at 5:30 a lot less, usually it's more like 6:20, but we have major nap struggles during the day.

Good luck. I wish I had a magic pill or spell I could send you. I'll think of you next time I'm up at 5:30.

I feel your pain........but not sure if you can get a baby on a schedule that is following down to the minute....sounds like your main problem is the waking up at 5:30 am - the baby is sleeping on time, not waking at night, napping fine but wakes up too early.......this might we his body clock......he may truly be hungry.....expects to be fed and then go back to sleep especially if he starts acting sleepy again around 7:15 am...your right he maybe waking up to nurse and if you did nurse at 5:30..he would probably sleep again right after........our LO too gets up around 5:30-6 to feed - I give him the bottle, he finishes it and rolls over to sleep again.....his dr say the only way to break the habit is to let him cry and fall asleep again...but I just don;t have the heart to do it...if he slept at 8:30 and then wakes at 6:00 to feed then I don't mind going up to his room and feeding him and then coming back to mine for another quick snooze for myself or even get a head start on the day.......I know my response doesn't offer solution but Good Luck!

I've been there & done this same thing.
The only difference is I got up w/him at that time.
Do that & your hubby will get his sleep.
As soon as you hear your son cry, go get him out & take him to another room like the living room.
Your hubby will get his sleep & you will have to rest/sleep when baby naps.
He's tired of sleeping/being in his crib, is hungry and wet, wants to get out be w/mommy & explore.
Go with his schedule & your entire household will be happier.
I promise this stage will soon be over.