Tenants want to move in their things before the start date

[Guka Kagu]

The lease starts on December 1st, but the tenants asked if they could start moving in their things this weekend. I am still paying the mortgage on the property and the property is vacant. I asked them earlier if they want to start the lease from November 15th, but they said they can't do it before Dec 1st. I don't know what to do? I don't know if I should ask for prorated charges or not because it sounds greedy since nobody lives at the property. I also don't feel comfortable letting them move in their stuff before the start date, but then I don't want to start this on a bad term.

Please help me thank you!