Your credit score is calculated using the information that’s available the same day your lender requests it. That means you can work on raising your score on a daily basis.
You can obtain a copy of your credit report from any of the major credit bureaus — TransUnion or Equifax. Here’s what it takes to start improving your credit file:

1. Tell the CRA in writing what information you believe is inaccurate. Include copies
   (NOT originals) of documents that support your position. Clearly identify each item in
   your report, state the facts and explain why you dispute the information, and request
   deletion or correction. Send your letter by certified mail, return receipt requested, so
   you can document what the CRA received. Keep copies of your dispute letter and
   enclosures.
2. CRAs generally must investigate the items in question — usually within 30 days. They
   also must forward all relevant data you provide about the dispute to the information
   provider. After the information provider receives notice of a dispute from the CRA, it
   must investigate, review all relevant information provided by the CRA, and report the
   results to the CRA. If the information provider finds the disputed information to be
   inaccurate, it must notify all nationwide CRAs so they can correct this information in
   your file. Disputed information that cannot be verified must be deleted from your file.
3. CRAs must make necessary repairs to all appropriate items. If your report contains
   erroneous information, the CRA must correct it. If an item is incomplete, the CRA
   must complete it. For example, if your file showed that you were late making
   payments, but failed to show that you were no longer delinquent, the CRA must show
   that you're current. Or if your file shows an account that belongs only to another
   person, the CRA must delete it.
4. When the investigation is complete, the CRA must give you the written results. They
   must also give you a free copy of your report if the dispute results in a change. If an
   item is changed or removed, the CRA cannot put the disputed information back in
   your file unless the information provider verifies its accuracy and completeness, and
   the CRA gives you a written notice that includes the name, address, and phone
   number of the provider.
   
   At your request, the CRA must send notices of corrections to anyone who received
   your report in the past six months. If an investigation doesn’t resolve your dispute,
   you could ask the CRA to include your statement of the dispute in your file and in
   future reports.
   
5. In addition, tell the creditor or other information provider in writing that you dispute
   an item. As with the CRAs, include copies (NOT originals) of documents that support
   your position. If the provider then reports the item to any CRA, it must include a notice
   of your dispute. In addition, if you are correct and the disputed information is not
   accurate, the information provider may not use it again.
6. If your credit file doesn’t reflect all your credit accounts, work on updating it. Most
   national department store and all-purpose bank credit card accounts will be included in
   your file, but not all creditors supply information to CRAs. Some travel, entertainment,
   gasoline card companies, local retailers, and credit unions are among those creditors
   that don't. If you start improving your credit history today, you can look forward to
   having lower loan rates tomorrow.