Well... most plants outside start flowering before 12/12. I think the fall equinox was september 23 which is when alot of plants are already finished. Most plants start flowering when its around 13/11. If you live in the UK then itll probably be too cold in about a month. Cannabis won't grow if it gets below 50 at night.

Im assuming thats how long a plant would have to develop its buds? Typically plants finish between 50 and 70days (excluding some pure sativas) whcih is usually around october