Here is how I manage setting my Stanley 48 and 49. I set the edges back slightly from the sole and set the keeper screw snugly but not hard. I set the plane onto a previously planed and squared stock edge just like I would while using the plane. Using a light, soft (brass) hammer I lightly tap the blades down until it takes a light cut. I continue repeating the process until I get the cut I desire with each of the cutters and then tighten down the retaining screws. If I find the blades have advanced too far during the process I loosen the retaining screws, back the blades up and repeat the process as necessary. You do want the action of the plane to not be difficult or destructive to the joint but you also want to take an aggressive cut to minimize the amount of time to create the joint. It really is a judgement call by the user and the tongue normally won’t bottom out in the groove. The fit of the joint need not be extremely tight or precise since it is usually left unglued to permit wood movement.
They are usually pretty sweet planes to use unless they have been damaged in a way to throw off the fence alignment or if the blade forming the groove is undersized for some reason. Watch your grain direction but minor tear-out normally isn’t an issue since it normally occurs within the joint or on a corner that is often eased or chamfered. As in most planes, a little wax can help in use.