my plant is male

my plant is male but i want to keep it for seed...how long will it take to get seed from the plant...do i have to keep it in flower mode?
can i still smoke it...not that i really want too.

Sure you can smoke it, but the most you will get is a headache.
Males dont produce enough THC to get you anywhere.
As for the seeds, you would need a female too.
Seeds result from females collecting male pollen to produce seeds instead of buds.
If you let the male flower, the only thing that will happen is you will end up with big sacks of pollen ready to destroy any females that you may have.