Every showing is booked in groups with 10-15 min time slots, 2 per slot.

We schedule 10 showings for a Saturday & Sunday, last minute cancels and I have the time slots filled same day.

would like to learn at the next available slot ... thanks in advance

I'd charge ~$1000 a slot for Jan-May (8-10 people), then short term the rest of the time.I wouldn't self manage, so I get the point on unique, well designed, charming places being a priority.

Let's say Saturday Jan 14 you will being doing showing, "to lock in a time to view the property please fill out and send back with your available times and I will provide you with a 30 min slot". 

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. 

I bet a lot of the smell is hanging out in the carpet and pad as well as in debris in the coil if filters weren't changed frequently.  

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.

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