When is the best time to request this?  If the reviews show that a provider offers PSE, could we assume that this could be requested during a meeting?  Or would advance preperation be required?

Asking someone if they like to travel to exotic places like, I don't know...lets say Greece, would probably require some advance travel notice. I know I like to prepare and maybe pack a few things before traveling.

Ask them before you show up and then verify on TER if anyone has posted that she will do Greek. Dont ask when you get there.  She'll come up with an excuse or wink at you and say 'next time'.