The landlord can paint his house anytime he wants. He must give you ample warning that they will need to get inside before starting if they will be painting inside. It would be in your best interest to move things away from the walls so nothing gets broken. Put any valuables in a safe or hide them so noone can see your account numbers etc. If you cannot be home while the work is being done. Remind them that nothing is broken or has paint on it so keep it that way. Even though they have your permission to enter to paint, it is still your place and they must respect your things and privacy. That means, if you don't smoke, it will be forbiden for anyone to smoke anything in your apt nor will they be allowed to booze it up. They will work in a professional manor and in a respectful manor or you will kick them to the curb. Make that clear up front.
