Soon I will be meeting a provider for the first time and I understand that it is wrong to talk about certain things like services before the meeting or even at the beginning of the appointment.  I like white lace and stilettos.  Respectively, at what point do I ask if the lady has these things and will she wear them for me.

Before the appt. Ask when you book it. It's ok to ask that she wear something you like.

There is nothing inappropriate about asking her to wear something special!

something like " I love ladies who are into lace and stilettos.."  and she should be able to get the hint

First of all discussing clothing does not seem inappropriate to me.  What I usually do is merely to mention to the lady that I love the sight of a pair of nylon stockings on a lady and leave it at that.  Any lady who does not understand simply does not care.

I'm a dress or skirt, blouse and heels kind of guy and always ask that the lady be wearing one or the other.  They have almost always accomodated my request.