I would say you def. want to give it a try. I've had to do the same thing this season, except where I'm at by now it's too late because the first frost can hit early.

1st off When does the first frost in your area hit? In some parts of Cali the first frost doesnt hit until Dec. If thats the case where you're at that gives you Sept. Oct. and Nov. which is more than enough time IMO. Just make sure where you're the plants will be receiving enough photoperiod, which throughout early Nov. shouldn't be a problem. The only thing you would want to avoid is plants with a long flowering time because that might push you beyond your window.

With 1 month of veg. and roughly 2 months of flowering you should be ok. The plants will start to flower as soon as they are mature enough because they'll almost immediately notice the rapidly decreasing hours. After a month they should be about a foot tall and once they go into flowering they'll double or triple in size. I personally have always assumed that late plantings flower more rapidly in a last attempt to "catch up". With 15 plants you would still have a decent harvest.. definitely better than nothing.