You could schedule showings during a time frame you are available and require people to pick those slots.

Their schedules fill up fast.I know everyday for commercial I have to plan the time slots for my clients.

They've missed a few slots in the past couple of months building in the route 24 corridor.

At check in they gave us a coupon for a roll of nickels to play the slots in the "casino" (read bar with slot machines) across the parking lot.

Also if you intend this to be a rental, be aware that condo associations often have limits on how many units can be occupied by tenants, so check with the condo management first as to how many rental slots are left if you intend it for a rental.

It seems to me that one of the harder slots to fill is a reliable/ honest general contractor.

It's almost and automatic slot machine.  ;-)  The roof is next, probably in 5 years or so.  

I check my "competitors" from time to time and there's a lot of empty slots in their calendars for the late spring and summer, just like mine.

It's not like you are stuck in some hourly or professional job with income slots that you are wedged into.

Take them out to lunch and show them nice glossy pictures with testimonials from someone who is in their slot in life and see how they respond.