Unless you are under the age of 18, a 3 year time limit applies. That is, you must bring your claim and ensure certain things have occurred within 3 years of the date of the accident.
The relevant legislation requires you to lodge a Notice of Accident Claim Form with the insurer of the vehicle at fault within 9 months of the date of the accident, or within 1 month of consulting a lawyer about bringing a claim, whichever date is earlier. If you do not lodge a notification within that time, it is not fatal but you must provide the insurer with a reasonable explanation for the delay.