nintex form time slot user limit

Hello Friends,

I am new to nintex. I am creating a nintex form with 4 time slots.

Each time slot should allow at most 5 users for selection.

Now the requirement is, if a 6th user tries to join to a time slot which is already full, a message should appear saying use other available time slot because current time slot has reached max 5 user limit.

I am trying to implement this using nintex controls.

Please guide me on how to implement this.

Thanks

Deepanwita