when and how to force flower

any help is appreciated
i have 8 2 in a half month olds waiting to be flowered, but i dont think the sun starts 12/12 in IL until mid sept

Are we being impatient? If possible, just let them veg until nature tells them to flower. If theres no way possible for you to wait, you'll have to cut their light cycle to 12/12 by either moving them into a shed or the house or by covering them with a garbage can or something.