After you download your credit reports, it takes several hours to review them for errors. Then, you must gather documentation and draft dispute letters, which could take up to a week or more if you aren’t already familiar with your records. Depending on the item and the reason it's in your credit history, this could involve writing a short letter or performing significant amounts of research.
Credit scoring models usually take into account how much you owe compared to how much credit you have available, called your credit utilization rate or your balance-to-limit ratio. Basically it's the sum of all of your revolving debt (such as your credit card balances) divided by the total credit that is available to you (or the total of all your credit limits).