The time to plant outside is in the spring, post-spring equinox (though they may be started inside earlier), after the last danger of frost has passed. Call a nursery if you're unsure when that is.
4/20 is an ideal date.
as far as I know, the cycle of the moon has nothing to do with the best time to plant marijuana. I know it doesn't have anything to do with when to harvest.
Farmers have planted and harvested crops "by the moon" for centuries. Though there isn't a lot of scientific evidence to support it, many still believe and some reports do support it.
I think the general "Rule of thumb" is plnt root crops, carrots, 'taters, radish, on a "waneing" moon(on the decrease, from a full moon) and flowering crops in the "waxing" moon(not sure of that term, but while the moon is increasing from a new moon toward full).
I have also read that clones taken and rooted during the "Waxing" moon(if thats the correct term) have greater survival rate and root faster.