I hope you've got room to move your light up. I would have flowered long before now although that's because I haven't got much headroom in my grow space.
From what I have read on the subject the consensus appears to be that you should wait until the plant is sexually mature before going 12/12, which is why clones (which are almost always going to be sexually mature plants) can go straight to 12/12 once they have a proper root system down.
If you go 12/12 before sexual maturity then you will still have to wait for the plant to be rushed through it's maturing process before it will flower. This means that you may not save much time. It will also obviously mean you have a smaller plant, although that is a benefit for many people with very limited space.
The best sign of maturity is when you start to see branch growth which is asymetric (to start, the branches are always in pairs..after maturity some, but not all will start to grow without a "partner" branch. It isn't always obvious though, and some plants don't really show it clearly, so it isn't foolproof.
Desired plant height is usually the number one consideration when deciding when to take plants out of veg and start them flowering.
They're looking great by the way. Forgot to say
