Maybe a quick reply that you will be available during the scheduled visit time. He needs a reminder that it is not at his whim!
I sent: "I always have her available during your scheduled visit time. Not a problem."
Me: 46 FWS: 36 Married and Divorced 4/07, Pregnant 7/07,False R 7/07 Baby Girl born 3/08 Kicked him out because OW: 7/08 5/10 He realized what he had and lost. Moved home! REMARRIED 3/14/11!!