Hello People ... pretty difficult situation. Help is needed

Hello People,
i want to do a outddor grow
so today is the 12th of june and im in the Balearic Islands In Spain
So i just put my seeds for germination .. these are regular seeds of some weed which has left a looot of seeds
SO now i just germinated arround 20 seeds ..
And NOW my first question is can i find out by putting the seeds into flowering period when they are like as big as clones (10-14cm) which sex they have ..? .. i know how to put them into flowering period ..
so after i just put them back into the veg .. when i found out whats the matter .
That would be one question
NEXT big question is that i want to make them grow the fastest as pssible ...
im open to every kind of Growin unless hydro or aqua or dwc or smth..
so i even can give them any cemicals which let them grow reeally fast in the vegetation period..
Dont know .. in the middle of august they will go into flowering naturalwise ..
So i have only 2 months and 2 weeks for everything ... SO if the think with the unnatural short flowering period breaks the vegetation period for some time then i would say i just grow them all up..
But yeah just speak a lot to me im happy to listen to everything what could make me wiser
Thankyou

I don't think it is going to happen. You could try to veg indoors but if that isn't an option, you have what the sun provides. hydro, etc won't do anything and not sure how you could do outside.

Trying to sex will waste time. If you are growing outdoors, plant them all, When they show sex, pull the males.