There is a strictly legal answer and then there’s a practical answer to that. Assuming you’re an adult and the case is being brought against a private individual or private entity – you have two years from the date of the accident to either settle your case or file a lawsuit. That’s called the statute of limitations. If it’s a minor child, if the claim is against a private entity or a private person, the minor child has until the age of 20, which is until the age of majority (18) and two years from that date to file a lawsuit or settle the case.
If the case is against a public entity such as a county, or a state, or a city, then you have to file a claim within six months from the date of the accident and then file a lawsuit within a prescribed period of time after the claim has been rejected which it universally will be by the governmental entity. That’s the strict statutory legal requirements for filing a claim.
You need to get your evidence together and get the appropriate experts together whether it might be an accident reconstruction expert, or bicycle repair expert, or some kind of medical experts on your injuries and damages. Getting that assembled is something that is done best while the evidence is fresh, and there might be issues that take a long time to develop, such as how a serious injury might resolve that can sometimes take a couple of years to even figure or play out over the lifetime of the person. The sooner you start to put your case together and put the other side on notice and find out what their position is, the better off you are and the better off you’ll be able to put your case together and assert your claim.