When to flower?

Finally stress free and in at tent(closet to forest to tent), Getting an even canopy, are they ready to flip? They are closing in on 2 feet i believe. Looks 4 weeks old although they ? Read somewhere that you double your yield for every 2 weeks you give it.
I should give it a week more right?
Sorry about lighting, they are healthy green

Depends on what you have for vertical space. Expect plants to double in size during flower and then confirm you'd have enough room between the canopy and lights after that doubling. That's just a quick estimate as some strains can triple in size. GL

Looking good. Fine to flip any time now.