Landlord showing apartment 25 days before we vacate!?

In Ohio is it legal for the landlord to show an occupied unit a month before the tenants vacate? Do they have to tell you how many people are looking at the place? Can they legally make you leave for them to show the place? We have had no problems with our landlord before this but now with the for rent sign up, we have people coming to our backdoor to look in! The did not even put that it won't be available until November on the flier!