Setting Up A Booking Calendar

Hi, I'm attempting to set up a booking calendar so that equestrian clients can book for me to shoot short reels for them at a competiton/clinic.  They have to pay in advance.  

On the clinic day there will be sessions with up to 4 people in the session so I need to allow potentially 4 people to book.   Time slots are not regular hourly times, some are 1hr, some 1.5hrs  and some 45 mins

I've chosen the Special Event option and would then like to list times for them to chose from so I know which session they are in but I seem to have to create an event for each time rather than have times listed under the one day (hope that makes sense).  Is that what has to be done or have I missed something?