N.K.
If there is no reason to move him and he happily sleeps there, keep him in his crib for as long as you can.
We recently had to switch to a toddler bed (at about 27 months) as my son refused to sleep in his crib. This happened after he was sick one night and he preferred to sleep on the floor rather than go in his crib. He slept on a mattress on the floor for some time, and then we put together a toddler bed together with him. He was very excited and loved the big blue teddy bear bed :-)
So I would recommend to get him involved in making/selecting the bed/sheets etc so he gets excited, when switching to a big boy bed.
GL!