My experience is that February is the best time to root Tsuga's.
Use 1 year old wood which doesn't need a special treatment.
Good luck!

Personally, I am of no value because any cuttings I've tried failed, howerver, in The Cultivated Hemlocks by John Swartley it says:

"The date of taking cuttings does not seem to be at all critical, success being recorded from cuttings taken in Summer, Autumn and early Spring. A fairly high level of auxin application is apparently of advantage (2 or 3% of the active ingredient in a talc mix and similarly a higher-than-average treatment in the case of a liquid quick dip)."

It also talks about how Don Smith of Watnong Nursery got 80-100% success using a Nearing Frame built deeper (20 inches deep) by taking cuttings in late June to early July "when the first early growth has matured and darkened, and before the second annual growth begins."

But it also talks of success with November cuttings, so go figure. It also mentions its probably more difficult to grow them on than it is to get them to root.

tj