I think you are confusing full custody with no visitation...he can come back after any amount of time and ask for visitation regardless if you have full custody or joint custody. What you will want to do at that time is to ask for supervised visitation 'til he and child gets to know one another. As far as child support goes, that's a seperate issue and one that should be addressed. Get things moving on collecting the support he owes and understand that he should pay for the years that he didn't, those are arrearages if you have a court order.