It depends, If it a position i really need i play him right away, If it only to cover another player, i try him slowly, use him as sub, playing last 30/20 minutes, then a full game.

About the 2 playmakers, in one of my teams my ML/AML and my MR/AMR both have playmaker ability, they are always in my top scorers and top assisters, they score more that assist, but probably that is because of the position they play.