I think giving both yourself and him the most time possible with supervised free roam time to figure out what sort of behaviors might crop up that haven’t before is important. Also, if you typically let him out at certain times of day, try different times to see what he decides to do. From my experience, once the rabbit finds its niche spot for sleeping during free roam, it’s pretty low risk during those daylight sleeping hours. Once it’s awake, then its party time!

Does he have litterbox(es), water, and hay sources outside the pen?

Honestly, the biggest thing in this transition is to not worry too much. Make sure you watch to see what he would chew if you left him out for longer lengths of time but you really just need to try and trust him. Try to get everything off the floor you can and then cover the remaining baseboards and furniture legs with wood, NIC grids, or what I use- shipping tape. I have literally taped everything in my room and it’s worked great. I let my bun free roam in my room during the day and he is really awesome. He sleeps when I’m gone but as soon as I come back he gets energy, and then sleeps again when I leave lol. I tried free roaming him at night and he would be a perfect little angel and sleep until 5:30 EVERY NIGHT. At exactly 5:30 he would start playing with his metal food bowl, tossing things into his metal cage bars, digging the carpet, and finding something new to chew! Anyway, I’m sure he will be fine and just sleep if you let him free roam, just made sure he couldn’t destroy anything. Like Wick said, just watch him at different times of day and try to trust him.

Bunnies can definitely vary on this. Some are just not big chewers and can be more or less trusted not to get into trouble. Others not so much. Take things slowly and gradually increase his amount of freedom. If he does well, then he can keep free-roaming during the day. And there is nothing wrong with a bunny “going to bed” at night. The cover of darkness can be so tempting for bunnies to get into trouble. Plus they tend to be active early in the morning when you’re still sleeping. There is nothing wrong with having stricter boundaries during this time.

“The cover of darkness” …. so true @LBJ10 ….

I can’t stress enough what the others have said about observing him closely while he’s out at different times and for different lengths of time. My bun has never had anything but the complete run of the house, and he’s never gotten into any real mischief (I think he’s just lazy that way), but there are definitely times when he’s way more active and could easily bump into a table leg or run underfoot etc so i must keep a closer eye on him. Observation is your best tool. 🙂