I just sampled my tincure, caught a nice buzz from 1/2 teaspoon (3ml).
What I did:
1.5l 99% ISO, stuck it in the freezer for a couple of days.
Took about the equivalent of 30g good weed, baked it in the oven at 135F until it was overly dry and crispy. [135F will decarb the weed, but not evaporate the CBN's(?)]. Busted it up like I was going to roll it, put it in a big jar and put it in the freezer overnight.
Next day, I poured 1L of ISO into the jar with the weed, shook it (3 times in 15 minutes), and put it back in the freezer.
Strained the mixture, and rinsed with the other 1/2L of ISO. Then I filtered the mix through a coffee filter (takes several hours).
Put the mix in a large bowl, and set the bowl in hot water to evaporate the ISO. CAUTION - This step needs lots of ventillation and NO FLAMES.
I then mixed the thc residue with 250ml of 151 rum.
So I figure that if 1/2ts gives me a buzz, 1ts will get me high, and that means that 250ml = apx 50ts = 40 to 50 good highs.
I don't drink the tincure, I put it under my tongue (burns) a few drops at a time until I get the desired results.