Tenant turnover. How do you know they'll actually leave?

[Megan Brooks]

Landlords- how do you handle turning over a unit and ensuring your tenant is actually going to leave at the end of the lease? Currently I have a lease ending 7/15 and want to have the next tenant in on 8/1. I will start advertising the property online, current tenant is not being cooperative in showing the unit. I don't want to sign a lease with someone and then not have the current tenant actually gone on 8/1. How have you handled this in the past? Is it best to wait until we know the tenant is out to start marketing it? I haven't had to do this before as my current rentals have had the same tenants for years.

Thanks!