If you pay off those balances, your score will rebound within 3 months. Just depends on how fast it gets reported to the credit bureaus. Paying down or off credit card debt is the fastest way to get a score boost. Applying for a new card will generate a hard inquiry which can cost your score up to 10 pts.est Answer: How fast your score improves and to what level depends on a few different factors. Credit Utilization-You want to keep your running balance (if you can't afford to pay your credit debt in full) at less than 30% of your credit limit.