I think the only thing you shoud "shoot for" is eating healthy nutriitous foods in normal sized portions. Really tracking them and being honest with yourself. I think you should also "shoot for" adding exercise and activity to your daily life. Those are goals that you KNOW for sure you can obtain. That's what you have control over. Now IF you do those things, you are sure to have a nice weightloss come the end of October. Who knows how much? 25 lbs? 30 lbs? Maybe a little more, maybe a little less. Whatever the case, you will be feeling and looking so much better. The new healty lifestyle will become part of your life and that will be your new normal. So no matter how much weight you've lost you will be well on your way to a better, healthier, fitter and more active you.
Good luck. You CAN do this. The end of October is plenty of time to make a substantial change in your life. I look forward to hearing about your progress.