Hip Hop Recovery - The post leg will come foward to try to recover balance under the throwing shoulder. Let it, then let the extended throwing arm gently sweep down and back. The stride is not the trigger, just a reaction to maintain momentum as the body tries to recover balance. Don't overstride, don't even try to stride - just let it happen. Front leg strides forward mostly as a counterbalance to body position over back leg - this keeps the throwing shoulder supported over the hip.
Front leg comes down as a reaction to upper body momentum.
Simply fall forward - it's less important that the chest is over the lead knee and more important that the throwing arm has the right line of travel.