Early Lease Termination Fee

[Roopal Shah]

I have a tenant who asked to end his lease a month early. I do have clause in my lease that allows for this with a payment of an Early Lease Termination Fee. We were able to get new renters in  & will only have 6 days of unpaid rent which we are charging the old tenants. The old tenants have agreed to pay this fee in lieu of the 1.5x months rent fee that was listed in the lease.

But now the old tenants have stated that they will not be paying the fee until 30 days after the new tenant's lease starts. So my question is what is the normal amount of time that I should expect payment of this fee? I should have clarified the pay by date in the lease addendum but just assumed the tenants would pay the fee by the end of the lease.