Registration limit to 4 users

Registration limit to 4 users

hi,

I am new to creating form. I would like to create a very simple form with the following options

1. Today's Date
2. Full Name
3. Phone
4. Email
5. Type of test
6. requested date
7. time.
8. Remained seat for the current date.

now I want to make 6. Requested Date so that only 4 people can register for one day and the time should froze in 9:00AM and when someone try to fill the form and put their desired date of request, the form should show how many seats are available for the mentioned date.

Could someone help me with this?

Thank you in advance