Best time to send out Non-Renewal Notice

I am going to be sending out a non-renewal on a lease that expires June 30th. Initially I thought I'd give them notice after I collected rent this month. Then I thought it might be too much notice. Locally, all we need to do is give them 30 days notice. Any thoughts?

I don't feel like I need to give the tenant an explanation because the contract is over.  Do you disagree?