If it has only been two months, you may want to wait a few more months to have a more solid case until you file for a custody modification. Court orders definitely don't "change themselves."

If you think it would incite mom to put up a bigger fight, you can consider waiting until after the custody modification occurs to file for child support. Provided you actually get the change you are seeking, simply go to tye clerks office after the custody trial and file the paperwork before you leave the courthouse that day, and ask that support be retroactive to that date. Child support is considerably easier to modify than custody, and it might be easier to clear that hurdle first. Don't bring up support at all with mom before that if its going to cause issues.