Got physical custody and want to move.

I’m sure this has been asked before. I just recently got physical custody of our 3 year old. In the future I would like to move closer to my parents about two hours away. His mom has not been able to go a full 24 without my help in some way. She seems to care more about how she looks for her next date than she does about our son. My parents watch my son every weekend while I am at work. If we did actually get to move my intention is to sign him up for part time private school.

Any move out of county has to get permission from the court. What should I do to have a better chance of having my relocation request granted.