This all depends on what experience you are booking as timings vary from package to package and what location you are doing the session in as each venue will organise the day differently.
Typically, if you are looking at one driving session in a Supercar of around 3 miles, you can plan to spend between 5-10 minutes behind the wheel.
However, you should allow being at the venue for between 1-2 hours for your welcome and introduction, sign on, and suggested arrival time of 30 minutes before your experience starts. So, in total, you can expect to spend between 1-2 hours at the venue, but this will be dependent on the precise experience you are booking.
Additionally, on busier days such as weekends, there can be a short wait between sessions, especially when you are driving more than one car as you'll need to allow a bit of extra time for signing on and another briefing.