given the size of your pots and the limited space you have going vertical, I would say you can and should flower sometime in the next few weeks or you will have a time with trying to tie the plants away from each other so they don't grow into themselves. You have some thick bushy growth so I would flower soon.

Also, what is the deal with the air cooled light above? It doesn't look like it is on, but you have a smaller flourescent light that is giving them light right now correct? I would recommend switching to an HPS light or maybe use the one that is hanging above if it offers more light. You were probably already going to do that anyways.