I'm on 2mg/day (films) and I chip on dope about every other weekend (snorting/smoking). It depends on the opiate for me but I don't get that much of a block if I've waited at least 8 hours. I try to wait at least 16 hours after taking it because then I definitely don't feel the block. I'm sure it varies person to person, what opiate they're using, and the r.o.a. At 0.5mg/day, after 8-12 hours I would think you'd be good to go. Definitely after 24 though.