Yes, you can offer the raised rent price to them in August. They may balk at it, but it's legal. To just raise their rent without notice nor giving them time to vacate is illegal. So, yes, you can give them those two options. It depends on your state law, but I know for sure you can't raise rent in August and would have to let them know by August 1 if you were raising it for September and give them the option to move out by September 1. Some states require more notice.