From my experience I'd say that most (if not all of them) privats in Prague works more by an appointment, there won't be usually any free girls hanging about waiting for random customers to drop in. Those girls which are there, are busy with other customers. Privats are not exactly like brothels, business model is slightly different.
That's why booking beforehand is needed. And they always ask for a confirmation (a call/sms) 30-45mins before scheduled meeting.
Only once i had my booking cancelled, or to be more correct, re-scheduled for the following day. It occurred when i was making my confirmation via sms and i got sms back that said something like: "sorry, we messed up our schedule and MissXXX isn't available today but tomorrow. Would you like to have MissYYY instead?". Which i declined 'cos i was hell-bent on fucking that one special young blonde girl i saw the previous day at the gang bang event on that same privat but unfortunately she wasn't participating that day, only pouring drinks. Luckily someone told me that she is indeed working the next day so i made an appointment for her right away.
Privat was TopPrivat and for some strange reason she wasn't even listed on their webpage. So if i wouldn't have attended that gang bang party the previous day, i would never had even known that there is such a gem available.
I don't think she was even 20yrs old, she looked so young and innocent and had a very pretty face. Little too shy for this kind of business, definitely not a pro but more like a schoolgirl having sex for the first time, that's how it felt to me. Which was absolutely great in its out of the ordinary experience. Even the fact that she didn't speak a word in English didn't matter. If anything, it only made the whole experience even more exotic, in a good way.
I had her on sunday and sundays are for some reason cheaper usually in Prague's privats, so i booked full hour (which i normally won't do) for 1300kc AND i got even 300kc off the price because i had to have my original booking re-scheduled so i ended up paying only 1000kc (less than 40EUR) for full hour with that amazing beauty. That's how you should handle your business and your customers!
I've been a loyal customer to TopPrivat ever since and i only wish they would hold these GB-parties more often than only once a year (and with a predictable schedule, now they are having those whenever they feel like so it's impossible to schedule your trip to Prague for that).