Tenant not moving in after paying first months rent

[Derek Carroll]

Tenant decided that they can't move in to one of my rentals after paying security deposit and first month rent. Lease says deposit not refundable but not sure about the first month. Technically they are breaking the lease I would think but then again it doesn't start until 6/1. I plan to talk to my attorney but wanted to see what everyone here has done in this situation. Do you refund the first months rent and keep the deposit?