Just in case there is any confusion, there are no time limits for applying for VA disability benefits. When you apply may affect the amount of retroactive benefits (lump-sum back pay) you can receive, but there is no time deadline for you to file an initial claim for disability benefits.
There is also no time limit for applying for dependents' and survivors' benefits. Dependency and Indemnity Compensation (DIC) is available to certain survivors of service members who died on active duty; died from service-related disabilities; or who were being paid 100% VA disability compensation at the time of death. Even if the veteran was not receiving VA disability benefits prior to death, I have personally obtained DIC benefits for widows by proving the cause of death was related to service. This is especially helpful to dependents of veterans of the Vietnam War who died of a condition not automatically recognized by the VA as one caused by expposure to Agent Orange. It is still possible to provide proof a Vietnam veteran's death was caused by herbicide exposure sufficient for a widow to obtain benefits.
There is also no limit to the number of times you may apply or re-apply for disability benefits. If you have been previously denied disability or DIC benefits, you can still apply to have your claim reconsidered any time. New and material evidence may be required in order to officially reopen the claim or be granted an award, but an experienced VA attorney can assist you in developing your claim and obtaining the necessary evidence.
If you are already service-connected for one or more disabling conditions, you can also apply any time for an increase in your rating or for another related or unrelated condition which may be service-connected.
If you have already applied for benefits on your own and your claim or claims are still pending, you can still contract with an experienced VA attorney at any point to represent you. Ask any other veteran who has tried to navigate the VA waters on their own and you'll likely conclude that it is in your best interest to obtain an experienced VA lawyer. Remember, while there is no deadline for filing a claim with the VA, there ARE many different deadlines for appealing VA decisions or responding to VA communications. It is best to contract with an attorney as early in the process as possible for best results. Waiting until close to a deadline is not a good idea and may cost your tens of thousands of dollars in retroactive benefits.