For most former service members, the trick is to verify the injuries and to apply for benefits as soon as possible. I waited a little over 10 years. The VA denied benfits based on the opinion that other events after military service may have caused or contributed to my current disabilities.
It also bears note that there are 2 ways to apply for benefits. Service connected disabilities are the toughest to get. Non service disabilities are easier, but benefits are usually limited to non monetary aid. Pensions are based on need, not as compensation.