males do show their sex a few days before females do.. but as long as you inspect your plants often, you should notice its balls before it has time to pollinate your females.. you can have a plant flower just to know the sex and then put it back in veg, but i don't know why you'd want to do that with a male.. if its a female, that can be a bit stressful for it. if a pollen sac does pop, fan or not, thats not good... just get them out as soon as you realize they're male..