If you're shooting for a 730, you're going to need a 50 in Q to go with your 40 in V. Even if you get a higher score in Verbal (say, 43) you'd still want to hit 47-48 in Q, at least. After all, you want a balanced score that won't raise any doubts as to your ability to complete the quantitatively challenging classes that all MBA programs will throw at you.
I hate to be the bearer of bad news, but I would advise you to reschedule and give yourself a couple of months. Go hard on Quant, starting from the basics (OG13 type questions) and working your way up to 700-800 levels. Make sure you work on AWA and IR just a tad, since it would be a shame to pair a 730 with a dismal essay or IR performance. That being said, I doubt that someone who is scoring a 40 in Verbal will have much of a problem putting together a good essay in 30 minutes.
Furthermore - don't try to overdo the studying. Unless you have remarkable stamina, 8 solid hours a day will not really impart more wisdom than 4 hours, as you tend to slow down towards the end. Pace yourself and develop good study habits, and it will pay dividends down the line.
I'm sorry if this isn't the sort of news you were hoping for, but hey - what do I know? I could be totally wrong about all of this.
Regardless, I wish you the best of luck in your GMAT journey.