It's very difficult to go up 300-400 points in 2 months. It's not absolutely impossible, but it may not be a realistic goal. It depends in part on *why* you received that score in the first place. Someone who scored 300ish after minimal preparation might see a quick improvement with some serious study. If you ran out of time on the exam, or if there were certain major question types (e.g. Data Sufficiency, Critical Reasoning) that you didn't know how to do at all, you also might find it easier to improve your score. If you did your best, knew how to handle the major question types, didn't run out of time, and still hit that score, you may have a longer road ahead of you.
In any case, you can certainly benefit from working through our course again. Using Interact, you can proceed just as if you were enrolled in the course, working through all the materials as assigned in the syllabus. If you are free to work full-time, you can spend the extra hours doing additional practice and--most importantly--reviewing your work. This becomes increasingly important as you move further through the course. Ideally, in each practice session you would flag some problems for later repetition/review, so that as you were working on, say, week 5 Algebra, you might also be reviewing questions from weeks 1 & 2.
However, I have to ask what you will do if you aren't approaching your score goal. Will you delay your application? Will you apply with whatever you get? It's important to ask yourself this now. It's great that you have lots of study time during the week, but the end of October is only 2 months away, and that's a very short time in which to make a really big improvement.
I'm happy to give more detailed recommendations if you let me know more about your particular situation. In any case, I wish you the best of luck!