How do I work with schedules and reservation calendars?

I have to insert a schedule in my form but how do I work with availability. If a person pick a date and 2 people pick the same date? Is it possible to make something that shows the user that the date is already picked?

I think you are looking for one of the following widgets.

https://widgets.jotform.com/widget/date_reservation

https://widgets.jotform.com/widget/multiselect_grid

The widgets disable the already selected date/slot so that the user can select the open date/slot.

Could you give it a try and see if they work for your requirement? Let us know if you need any further assistance. We will be happy to assist.