sure you could, but why would you want too?
you would get a short lanky plant, that would start browning from the bottom up, halfway through flowering, that woldnt yield anything.
6 inch square pots, Veg until 3 nodes, clip the top and flower.Go with a short strand, lowryders or an indica. Still a good chance you run out of space.
The only real reason to flower early, is to sex a mother, by flowering her clipping.