Most folks will feel activity around .75 gram, but it's (probably) not what you're looking for.
Even w/in a particular flush you can have a lot of variation in potency- I'd imagine commercial producers would have narrowed down to a particular clone, which would be relatively consistant-ish. A lot of small scale stuff is done from multi-spore, which is pretty much a crapshoot w/ the center of the bell at average potency.
I'd go a gram, gram and a quarter out of the gate w/ a planned boost about 45 minutes in- by then you'll know if you're comfortable w/ your come-up. If ya are, go for another .5 g. If you're not- well, ya can always take more, but it's tough to take less.
Ya have a little time to stack before acute tolerance kicks in. You can always go for the gusto once your familiar with the substance.
And you can ALWAYS boost 'em with cannabis.