Well, if it is a true autoflowering strain, a rudellis cross, then you have very little time.
The green pendulous pre-flowers should turn white in a day or two and open another day or two after that. All things considered, you have around a week....I'm guessing.
If you are so inclined, and have the patience, you can use a very small pair of manicurist scissors, and castrate the boys as you see the balls emerge. Not sure why you want to keep the boys at all.
I have done this castrating in the past, for other hort endeavors, always find myself involuntarily crossing my legs while doing this.