2 Part Technique - The Folding Pass isn't necessarily an attack used to initiate against the Butterfly Guard; in a more realistic context, the opening for the move happens after some hand fighting or pressure from other passes. The time to strike with the Fold is when you notice one knee closer to the the mat than the other. Smash the higher knee down onto the lower as you bear your weight onto his legs and hips. In order to undo his hooks, you will need to maintain a tight domain over both sides of his hips with the Double Under Control. If he resists strongly against the fold, go with his movement and fold his guard into the opposite direction.