I always start adding points to Jan's set traps ability the moment I get him. The traps are really good! Haven't tried moving silently or hide in shadows (for the latter, I'd rather wait till Minsc gets it naturally due to his ranger abilities).
Jan is easily the most useful and adorable NPC
Wait till Jan gets the spike trap ability...
S
P
O
I
L
E
R
it dealt 70+ pts of damage.