Disable dates based on appointment slots.

2) How do i set up a appointment form to block the date once i have reached a specified target number of ppl. ( I.e say on 26/06/2016 I have 2 slots for appointment and each slots can take 8 ppl. Once I have reached the target of 8 ppl per slot how do i condition the logic to automatically give them the next best/available date.)

We don't have a feature that would meet this complex requirement. However, we have a widget that you might like to check: https://widgets.jotform.com/widget/appointment_slots 

Let us know if you need more help.