When John had first preached before his coming the baptism of repentance to all the people of Israel.
When John had first preached before his coming, х pro (G4253) prosoopou (G4383) = lipneey (H6440) tees (G3588) eisodou (G1529) autou (G846)] - rather, 'before His entrance' or introduction to public life, "the baptism of repentance to all the people of Israel."