When is the absolute EARLIEST I can identify male from female plants?

[PhoenixFlower]

Title.

I am planning my next grow & I've identified me some fine seeds, but they don't have any feminized seeds. So I'd have to opt for the regs.

When is the absolute earliest that I'd be able to know the males from the females? Do I have to wait untill flower? Or can I do it sooner?

 

[Habosabin]

I think there are services out there where you can send in samples when they are early and they can DNA test them for sex. That would be the earliest.

 

[Oldguy71]

After about 4-5 weeks from sprout you can give them a few days of 16/8 light and they should show a few pre flowers without going into full flower.

 

[Homesteader]

You will have about a one to two week window to identify and separate before it becomes an issue. Males will most likely show first under the same strains. Beginners are probably often scared as are large operations but it really isnt that hard if you have eyes on them as you flip to flower.