This is the fastest way I've seen published. I haven't tried it. If someone does, let me know how it works.

Dyeing with woad the fast way
*Drop the leaves into fast boiling water with a pinch of cream of tartar. Boil for 2 to 3 minutes.

* Remove the leaves and cool the liquid as quickly as possible.

*Add ammonia until the Liquid is yellowish in colour.

*Bring the liquid to 60 degrees Centigrade while adding ammonia until yellow again.

*Add sodium dithionite to deoxidise the liquid.

*Stir gently without splashing until a bronze scum appears.

*Put in the hot wet wool then remove it and shake in the air.

*Dip it again if not blue enough.