i watch my sinktip and leader on my backcast for the final stroke . assuming everything else is right, you need to wait on your forward stroke until the weight of the backcast pulls the L out of your sinktip and leader . i wait until it straightens and starts to pull the begining of the leader up from the water. then you are straight and you know you are fully loaded. if you have the L in your line it crears extra accelaeration in a different direction and flips the end of your line back downstream.