Dinner visitation

I have shared custody with my ex and during the summer we rotate weeks with the opposite party having a dinner visit. The papers do not specifiy what night the dinner visits it to occur…they only say weekday nor does it specify when the other party has to let them know about the day they would like the dinner visits. Last summer we verbally agreed on letting the other party know by Sunday so they could plan accordingly. It is now Tuesday and I have asked for a weekabout when he would like his dinner visit…is there a point where I do not let him have it. In the end he lacks communication adn the kids suffer