You would be surprised with how many people don't realise that you have had SMP after having it done, make sure you don't go for a aggressive hairline or to dark colour if this is something you want to keep private. We have had people that had sessions and their family didn't even realise they had the procedure done, they simply though they where growing their hair more or shaving differently, when you build up the look over 2-3 sessions its possible to do this slowly.