If he does paint your home by the agreed-upon date--which by now, would have happened, if it were going to (today is June 12th)--then you would have to pay him; in that instance, he would have complied with the contract (it doesn't matter whether he *also* painted your neighbor's house). If he did not paint your home by the date in the agreement (the 10th), then he breached the contract in a material, or important way, and that breach should allow you to treat the contract as terminated.