Why do it before?  If you do that, what happens if the service you will get from her is not worth a tip.  Search on this forum for 'tipping', there are numerous threads on the subject.  Personally, I do not tip, but I do take gifts.

LLAP,
Swim

Why would you tip her anything?

I guess if she drives a cab you would tip...but a prostitute?  Really?

As swim said...plenty of discussions on this topic.  Do a search and read till you're sick of reading.

FWIW...pay her her stated rates...have fun and then do it all again with another one.  Leave the tipping to those making minimum wage jobs.

If you do a search on it you'll find no end of threads on this subject.


Bottom line:

Most clients seem not to tip, and most providers are OK with that.  Some tip by bringing a present (Many gals have gift lists on their sites.) and many gals insist that your repeat business is the best tip.

My advice:  Tip if it makes you feel good about yourself to do so.  Also, a tip is in order if she gives you time and/or services above and beyond what her rates and activities call for.

It's all up to you.

First,   our time together goes a bit past the scheduled time, or my experience goes way beyond what I may have been expecting.   Thus, that type of tip is given afterwords.  I always try to present or give it to her very discreetly, and not make it a big deal or have it seem as though it's some kind of "reward".   Just appreciation and thankfulness for her wonderful company.

Second,   if we have seen each other many times, I always bring unique gifts just for her.  The price of which can vary a lot.  From very little or nearly nothing, other than some thoughtfulness and imagination on my part,  to several hundred dollars for an item that I know she would like or will definitely enjoy.  She is always surprised and never knows what I will bring next.   Kind of like what she does for me.    

I have no idea if this is "proper etiquette", but it makes sense to me.  And, it's a lot of fun for both of us.

Lastly, I think it's important to keep in mind that, a gift is NEVER intended to elicit better service.