A person must file an EEOC charge within 180 days of the alleged discriminatory event. This can be extended to 300 days in some states. However, most states follow the federal 180-day rule. Carefully check this and make sure that you timely file a claim. If you do not file a claim with the EEOC, then you lose your right to sue under federal anti discrimination laws.
This may be another advantage of filing a claim under a state anti discrimination law. For example, employees in Tennessee can bypass the administrative charging process and file a claim under the Tennessee Human Rights Act directly in court. Once again, this shows the advantage of having a good attorney who can help guide you through these important decisions.