D,
I always let my kids roll into bed with me,
As long as he spends the majority of the evening in his own bed you will not have any trouble,
He needs to know he can come to you,
If you keep changing his routine by sitting next to him he will never relax long enough to feel comfy in this new bed
Instead of sitting, cuddle him close bring him into your bed, and fall asleep, at somepoint try and carry him back to his own bed, so he wakes up in there, eventually his visits to you will dwindle down to very few.
When he wakes leave his door open, and put a few night lights in his room and the hallway, when you hear him wake call him to you, and pull him into the bed, after he quickly drifts off to sleep carry him back to his bed,
the key is having him wake in his own bed, thats how they get comfortable with the space, and every sound and sight is familiar to them,
Aslo making sure he naps in that room helps too.
Good luck
M
Mother of 3