If you were covered under him at his last job then you would be eligible for COBRA. You have 60 days (confirm that #, I can never keep it straight)to sign up from your date of non-coverage.
But it retros's back to that date. So if you lost coverage July 1, you have to pay the entire month of July so you do not have a break in coverage.
His employer has 30 days to mail out info--that he may have already received about the process. But I would call his previous employer directly to find out.
Keep in mind COBRA is expensive-100% of the insurance premium plus a 2% service charge. You may be able to find a basic policy for less $$, depending on what you need.