The only person you should be asking this question to is your engineer/technician if pushing. Generally I do not clear for advancement in throttle until I have the tug and towbar linear with the aircraft close to the taxiway/lane line. All aircraft are different, I watched a 777 with 115B's snap a towbar in a tight turn during pushback with one engine running and the other cranking. If it was a 737 or 319 I might not care.