That's one way to do it, if you have 2 grow areas so that you can keep a female alive at all times. Otherwise, you have to either grow from seed, or find another local grower who can house a clone mother for you. I know people who do that. Heck, I've got a strain backup agreement wiht a few of my grow buddies. It works out okay!
I would not really want to put multiple plants in one bucket. If one shows male, it's hard to get him out without damaging the roots of the others.
I have always sexed first and transplanted as soon as they show female. As the BOG says, "why waste work on a male?" lol.
If that big bucket is all that will fit, then after tehy show sex would be the time to stuff them in there. Angle the main stems away form one another to make trining easier if you have to do that.