I am a novice when it comes to outboard diy service although I have done my share of auto and mower service. Anyway, I own several service manuals for my outboard (it has the electronic spark advance). My timing is at about 9* at idle; should be 2*-6*. The Seloc manual says that it is not adjustable for 20hp and 25hp from 1994.5 to 1996. However the Merc OEM manual says that the mechanical advance models could be adjusted at idle and max but only refers to the max on the electronic spark advance models. For the electronic advance models, is the idle timing advance locked/tied in with the max timing advance (both increase or decrease when the timing rod is adjusted) so when the max is set, the idle is therefore set.
