The advantage of starting first and out pacing your opponents is that you get to drop off your incarnate in a position where it can "hopefully" get in some attacks of opportunity as the enemies charge in and soak up some damage for the party. The disadvantage of doing things this way is that your summons won't last until the start of the next turn and that should be fine, because it's one turn in which the opponents did not harm your party members.
At 10 wits you just use the incarnate to prevent enemies from fleeing by summoning it behing the enemies - but this strategy is more suitable for high wits conjurers because the incarnate could in theory land some hits of opportunities while the opponent is runing away. The disadvantage of doing things this way is that this strategem works best with conjurers that can fight in melee range not for back row casters.
For a backrow caster an Incarnate is like a panic button you hit so that the thing you summon can land some attacks of oportunity - my point is, you used incarnates and totems as primary damage dealers,when in fact they are utility skills aimed at hampering opponents escape and charge tactics. With the right party compositions and surface applications the incarnate can also serve as a source of healing (ice incarnates get heal, poison incarnates heal zombies).
