Hi Hun,
I think with the chair next to him he may be okay, but it's a little trickier with a LO in a bed. The choices are this:
If he keeps getting up, return him to bed without eye contact and use your sleepy phrase. This however in my opinion can be the drawn out way of doing things and is definitely harder work

. If it were me (IIWM) I would be inclined to leave him if he gets out of bed, see what he does, use the sleepy phrase and if necessary tell him "Back to bed please" so he knows the expectation. It may be that once he realises you aren't going to enter into conversation and you are staying on your chair, he will lie back down himself. The problem with the returning to bed is, it's a battle of wills and it is giving the LO attention, so you have to keep going until you crack it, which may be after your back is aching and your blood pressure is about to blow

Do you see my point

I have know LO's lie down and sleep on the floor rather than give in, and you know what that's okay, you can just transfer to the bed when they pass out exhausted usually

.
What's your thoughts on this

It may be that he doesn't even get out, but obviously this is a head's up so you have a plan whatever happens. Also you won't be able to let him out of the room, so if he goes to do that you would have to return him to bed or stand in the door, unless you have a baby gate there

WRT his routine, I'm guessing it's hard to say if he is low/average or high sleep needs at the moment

or not

Typically a LO of his age would be having an 11 hour night and up to a 2 hour nap, or over all sleep around 12.5 to 13 hours if they are ASN. While you're ST naps are going to be dependent of what happened the night before and how much sleep he gets, but I would certainly cap at 2 hours max, no matter what as it will encourage him to be tired enough at night and could help with a bit of luck. Remember to do things exactly the same for naps as at BT, this means by day 2 he has already done it twice and will be getting the idea

hopefully lol

Any more questions don't hesitate to ask Hun

I am at work on a Thursday evening unfortunately, but I will check Friday morning to see how it went.
Everything crossed for you

x.