What to Do when you Have a Qualified Applicant but they Can't Move In for 15 days?

[Dee Bral]

I have a qualified applicant in a rental in Virginia that is currently empty. The market has slowed and I don't want to turn away qualified applicants, but they can't move in for almost 3 weeks. Can I charge a holding fee until they move-in, in addition to the security deposit? Or is it better to charge rent before their actual move-in date.  I'm not sure what's best when the unit is sitting empty.  Thanks for any advice you can offer.