When he hath put forth all his own (otan ta idia panta ekbalh). Indefinite temporal clause with otan and the second aorist (effective) active subjunctive of ekballw. No need of the futurum exactum idea, simply, "when he leads out all his own sheep." They are all out of the fold. He overlooks none. Ekballw does mean "thrust out" if a reluctant sheep wishes to linger too long. He goeth before them (emprosqen autwn poreuetai). Staff in hand he leads the way in front of the flock and they follow (akolouqei) him. What a lesson for pastors who seek to drive the church like cattle and fail. The true pastor leads in love, in words, in deeds.