I think it’s a good idea to always use names that you know are less likely to conflict with something later in the future.
Btw, in your case, I would actually have an individual page for each client, with the names being person: full name and with a page property like is-client:: true, or a specific tag, or something like that.
Also, for linking, I would rely on markdown links, not just simple wiki links, just for aesthetics. It would look like this:
I met today with [Nicole]([[Person: Nicole something]]) to hand her the exercise plan I built for her
Lastly, If the client had some unique nickname, I would add that as a page alias