Current Leases and Increases on multiunit

[Ron B.]

I'm in the process of buying a 50 unit apartment building. My question is in regard to the current leases. How does that work when I become owner? Do I write up all new leases immediately under my new company name or do I wait until each lease expires one by one and do it over time? I also want to increase the rent on everyone, do I have to wait until their current lease is up? 

There is no clause in their current leases stating anything about what if the building is sold to a new owner.