The only character I kept track of is my Fire/Earth Dominator, who was fully T4'ed at vet level 7. That includes stealthing Heather Townshend's arc 40 times, and the rest were Mother Ship raids.
After crafting my 6th T4, I had 3 emp merits and a small handful of threads left over. Remember to use all of your resources, folks. It'll go faster that way.