If the other parent is not following the custody order, you can file for contempt. This is a hard road, however, if the other parent is consistently only a few minutes late. The courts do not like to deal with what they consider “minor” issues. If you want to pursue this, you will need to have evidence. You will need to document every time the other parent is late to an exchange or violates the order in other ways. Keep a log. You should also have evidence that you sent the other parent polite reminders of the exchange times. Once you can prove a pattern of lateness, then you can take the issue to court.
One custody arrangement that helps reduce the frustration of exchanges is to always have the parent whose custody time is starting responsible for picking the child/ren up at the other parent’s house. So long as you don’t have anywhere urgent to go, it is less frustrating to be waiting at your home rather than in some parking lot somewhere.