Well Tom,

You as the grower can begin flowering on day one if you desire. In nature plants begin and end life on roughly a 12/12 cycle and they turn out huge. You can top them multiple times to conserve space. How much of a yeild will you get with a 250 watter I can not tell you since there are factors like genes, pot size, ventalation and fertilzer which can effect your yield. Good luck and keep learning.

Loco