how long will it take my credit score to go back up?

I was out of work for a couple months and my credit card usage went way up. I wasnt able to pay more than the minimum payments until my last paycheck a couple days ago and I got it down to 350. My next one I will finish it off. Somehow after only a couple months of high wage my credit score is down all the way to 150. How long will it take to improve? I've never seen a credit score that low in my life.