Skirader

If a provider appears prudish during conversations in whatever media I use to contact them, that ends the discussions right there. If I wanted a date with a prude, I would go to a church social. Not that I have anything against the latter, which I can enjoy on its own terms ( for instance the food offered is usually quite good).

I totally agree with that.   That is how I operate as well.  Let the masseur or escort surprise you with his moves during the first session,  Sometimes it can exceed your expectations and desires.  Then, if you determine there is indeed a good match and an attraction, ask to turn it up a notch or two - if that is even necessary - in the subsequent sessions.
And as always, tip well if he goes the extra mile.

So new to all this but when does one bring up what they ideally would want in a meeting with a providers?  
 
Whats appropriate or inappropriate and what method of communication is preferred?  

depends on the situation, no? who is the massage therapist or escort and how do they present online. and what is the nature of the fetish? sometimes I am coy and other times up front in the first exchange of information. i prefer long term mutually satisfying relationships. its a delicate line when approaching someone new. and i travel on business so sometimes things need to cut to he chase for me. just don't your fetish get projected onto some unsuspecting dude and then get offended when things go awry.

in the 2nd text message... Just get to the point, don't waste people's time!

Ask as early as possible and be straight up about it. It’s quite annoying to have clients act in a coy way by opening with “hi how are you” etc and then slowly circling around what they want.
Much better to say “hi I’m looking for x and x etc are you ok with that? If so I’d like to book a session for duration on time, day  etc”. Don’t be shy about stating anything you want,  I’ve heard everything. 

welcome to the forum.......here are the profiles of both providers mentioned in the OP (conventional protocol here in the forum is to include a hotlink to the provider(s) being discussed) .......otherwise, I know nothing and have no plans to go to Japan or Florida.......
https://rentmen.eu/MGXXL
https://rentmen.eu/horsewhite
 

Thank you