Depends on who you intend to sue, what the violation is purported to be. Could be just a few months. You'll need to post more facts to get a meaningful answer.
NOT LEGAL ADVICE. FOR EDUCATION AND INFORMATION ONLY. Mr. Rafter is licensed to practice in the Commonwealth of Virginia and the US Federal Courts in Virginia. His answers to any Avvo question are rooted in general legal principles--NOT your specific state laws. There is no implied or actual attorney-client relationship arising from this education exchange. You should speak with an attorney licensed in your state, to whom you have provided all the facts before you take steps that may impact your legal rights. Mr. Rafter is under no obligation to answer subsequent emails or phone calls related to this matter.
This is actually not an easy question to answer. The court will likely look at your claim, see what is the similar tort, and apply that statute of limitations.
In the majority of factual circumstances, only the government is obligated to honor your 1st Amendment rights. Suing the government almost always requires the preliminary step of filing a timely notice of claim. The statutory period for filing a timely notice of claim is ordinarily 6 months to a year, but the time period varies with the identity fg the governmental entity that is to be sued and the facts and legal theory of the proposed suit.
You will need to consult a local civil rights attorney for more detailed and specific info because your post does not provide sufficient information to enable more in response.