Force Flowering Outdoor Plants

I am a first time grower. I have 3 pure sativa plants growing outside. If I allow the plants to run their normal course in growing outside, they will not be ready to harvest until the last week of October or the first week of November. I live north of Seattle, and the weather in October and early November is too cold for my plants to rise to the high quality that I'm looking for, so I have began to force flower the plants by bringing them inside to a small blacked out room at night for 12 hours and then bringing them back outside for 12 hours. I've been doing this for a week and I'm concerned because the plants haven't began to flower yet. I know if they were growing in a controled environment inside my home, they normally would have began flowering right away. Will my plants eventually start flowering if I continue to attempt to force flower them? If all goes well they should be ready to harvest the last week of September from the 10 gallon pots their growing in. It's quite a job having to bring the plants in at a certain time and then take them outside again 12 hours later, but if it works out the way I hope it does, it will all be worth it. So again, the question is: Will the plants start flowering pretty soon or will my experiment fail, meaning I'll have to let the plants stay outside 24 hours a day until November to harvest which will possibly result in higher yield but definitely will be lower quality?

It's been almost 7 hours since I first made this post, and there are no replys yet, so I added this paragraph at 8:52 PM to ask one last time for someone who is knowledgable about the situation I described to answer my question please. Surely, it can't be that difficult for anyone who is really an expert on the subject.

think about where a pure sativa grows. during the long, long flower season, they probably get closer to 11 on 13 off rather than 12/12. maybe try that instead of 12/12.

also, with a pure sativa, everything is gonna happen a bit slower, so have patience.

and maybe build a cart for those monsters if you can. 10 gallon pots are a bitch to haul back and forth. i had enough fun with 5 gallon pots earlier this year.

You are in a tough situation. I tried a sativa Durban poison strain about 5 yrs ago in ME (same October, November as you) and found carrying it back and forth wasn't feasible, so i created a grow area to fit the 7ft plant and finished it off inside October and November. You still have the time to plan on doing something like this, but you need the space.

Now i run Indica or faster flowering hybrids only outside.

Ive force flowered my plants for the past 3 years. I move them into a small shed at night then back out in the morning. Have had great success and grew some very nice tight bud all 3 years. Somethings to keep in mind:

-Because you started force flowering pretty early you will need to continue moving them in for a long while as the days are too long and you would risk reveging if you left them out
-make sure theres no light leaks in your room
-make sure your plants are secured/tied down or something because as they grow moving them starts to put some serious strain on the plants
-as others have said, be prepared for alot of work, 10gallon will be pretty hard moving
-Depending on your schedule you may want to consider having your wake up time the same as sunrise. So that if you cant take them out in the morning or your feeling too lazy to get up you can move them out at night when its dark out and let the sunrise wake them up for you in the morning.

I wouldnt stress though, worked very well for me. The plants are alot more flexible outside then people realize. There was a few times I had to move them in / out a couple hours early and it didnt have any obvious negative affects. They will be flowering in the nice hot summer sun, and it will pay off with tighter buds. Good luck with it, it can be a real bitch moving them everyday, but the price we northerners have to pay lol.