The simple answer is yes, you can flower now. You can flower from seed if you really want to. Flowering now will not stress your plant.
Just be prepared for a few things...
First, your plant is not sexually mature. It has not yet developed alternating nodes or preflowers. This will decrease your yield.
Second, the plant needs more light. It may have survived this long under very little light, but your plant is stretched to hell and you need more lumens for flowering.
Third, the plant needs a fan. Your stalk is weak and flimsy. It is never going to be able to support the weight of buds, regaurdless of how small.
You already know that your yield will be shit. So I won't bore you with those details. But, these basic steps will at least help you maximize what you do get.