my timber bamboo is shooting may 21 -is it p vivax or bambusoides?

i have a fine stand of timber bamboo in nj zone 7. it was sold as phyllostachys bambusoides. it is absolutely hardy, which means it might actually be vivax, which is hardier. but it has never had a broken culm despite occasional snow. i want to plant some on another property in nj, and would prefer to buy new rather than trying to dig it up. i have read the three differences are that vivax is hardier,vivax has thinner culm walls so tends to break in storms, and vivax shoots earlier than bambusoides. ted meredith says "Phyllostachys bambusoides is one of the latest shooting of the genus; P vivax shoots relatively early."

last year on june 9 it had new shoots about ten feet tall. i did not see those shoots the week before, but i guess 10 feet in a week is actually plausible.last year i cut a culm which measured 2" across, and the wall thickness is just over 1/4". it is entirely wrapped in brown culm sheaths.

anyone have a timber phyllostachys in mid-atlantic shooting now, mid to late may? which species do you thinks it is? or anyone sure they have either and know when it shoots?

by the way, my phyllostachys nuda started shooting around may 7.