If mediation doesn’t work and it goes to court, then courts like alternate weekends for contact for the exact reason you’ve given - so the child has quality time with both parents and they can go away etc especially when they start school. Also, if mediation is successful and you reach an agreement just be aware that it isn’t legally binding like a court order
Claim maintenance through CMS and in mediation give your reasons. He will have to take you to court if he wants any different. Be aware though, they may agree with him and it’ll be court ordered and you have to go through with it. From what you’ve said, he’s had had him overnight and they seem to have an established relationship. It’s very likely that the court will side with him or build up to an overnight arrangement after a few months etc. Unless there is a history of violence/abuse or a very good reason why he can’t do overnights
To start with, he is being extremely petty and childish in dealing with this situation. You still have to pay for you kid and see your kid even if you’re mad with the other parent, that’s just making the kid suffer for no good reason. I do however think you giving him one day a week and then taking it away could make him feel upset, I know ide want my child more then ones every two weeks. But I do understand you have family out of town and leaving Friday for the weekend is easier, so idk if y’all could just agree that week it’s happening that you need him this Friday, instead of changing it permanently to every other week? Or a month in advance tell him the dates you need him? Or whatever it is, because life happens and plans change for both parents and should be handled respectfully. But him doing all this probably won’t look good for him in court, and idk the entire story with him so definitely keep documenting everything.