Hi Tony, I was going to answer this anyway due to another poster had asked, but I'll take it from here.
Most of the time personally I'm working in a place where I am happy to see 'newbies' with 30 mins notice or before they have to start out, if they live further away. That way, if they do not come over, I've only wasted a short period of time. Most new clients will be able to book ladies like this.
If a client wants to pre-book, arrange a dinner date, an over night booking or an out call, I do generally ask for a referral. You can tell the lady that you have left a review on EI and where to look for it and she can check you out there, or you can say who you have met and if she knows that lady, then yes she will contact her and ask if you met. It's normally very straight forward and a simple, 'yes he is fine' kind of reply, nothing more than that.
Then with your permission I will text you to let you know the booking can go ahead, or I will wait for you to call back at an arranged time and tell you then.
Obviously if the referral is not used properly, then it's useless and of no help to the lady. It might be that there is no reply from the lady in question. I had that happen recently, but the client called 30 mins before the booking to confirm and I decided to go ahead, as him confirming was positive, plus there is a little gut instinct in there too, so that doesn't mean it would always go ahead with confirmation.