If you're happy to sit there until he goes to sleep then I'd recommend that too. DD has been in her toddler bed for several months now but we are on night two in her proper bed (king single) and I'm sitting with her right now. Just until she's settled then I'll sneak out.

It is a massive change for them so I personally think easing then into it by sitting with then helps. I worry a bit that our DD will end up relying on us to sit with her to fall asleep but everything I've worried about parenting wise has worked itself out and hey, she's only little now so I'm just trying to enjoy these moments while they last (even though it can be frustrating at times, lol!)