You need to be a duck and let that water just roll off your back. Be business like and have a process for viewing and filling out application. They do your procedure or too bad so sad. If they are interested they will comply. The rest are just lookey loos.
I would stay until 8:30 and no later. Some will miss appointments and that is good character information for you should they decide to return.
Don't sweat this...it's your house, you get to pick. Don't be in a hurry. But also beware of the one that has the monehy right now and wants to sign immediately.
Again stick to your guns and do complete background checks.