Well not exactly the same situation as you op but Im a sahm and dd was with me all day. When she got her pre school place in sept (she turned 3 in june) she went in the mornings for the first week then from the second week went ft. So in dd's case she was fine. And she loves it. I think you could see how he was at first and go from there.. Good luck!
I currently work FT and my son has been going to the same CM since he was about 8 months and he is very happy and settled there.
We are moving a couple of miles up the road to a new area at the end of next month, and so will be using this move to transition my son from CM to nursery now he has turned three. I have heard from friends that moving children to nursery when they have been at a CM is a big change for them.
Will it be too much of a shock to move him from FT CM to FT nursery (he'll go part time in the summer when as I'll be changing jobs and then will hopefully be on mat leave in Sept!) or should I put him in nursery for 2/3 days and continue to take him to his CM. We'd have to drive to the CM, but I don't mind the inconvenience of the extra journey time if it means an easier time settling him.