Our daughter was diagnosed with amblyopia at age 4. She had to wear glasses all the time and a patch for an hour a day to start. When the results were not what we wanted to see, she was able to use drops in her good eye to blur it for a period of a couple of days. It was the equivalent to patching for all of her waking hours for 2-3 days.
They will likely be more aggressive with your son's treatment since you've not caught it until now. I'm sure that they told you that here is a relatively short period of time to correct this before the neuro-pathways are laid down.
If he has to wear glasses and a patch, I would check into a patch called "frame huggers". They fit over the lens by attaching through the frame and are much more comfortable than the regular "pirate" patch. My daughter hated those (traditional patch) and would constantly peek through the gap and complain that it was uncomfortable. I would ask about the drops though. They were the most helpful and easiest form of treatment for us.
Our daughter's eye corrected in about 2 1/2 years with consistent treatment. Wearing the glasses is hard because in most cases when kids need glasses it's because it helps them see better. In this case the glasses are blurring the good eye to make the weak eye respond and it's really frustrating. They can't see better.They don't like it, but it's imperative to make them wear the glasses, patch, whatever, until it gets better because the time for correction is so limited.
Best of luck. Don't feel bad that you didn't know sooner that he couldn't see well. We couldn't tell until we took our daughter to a routine physical and they happened to do a paddle eye test. It was really obvious she couldn't see out of one eye, but how often do you cover one of your kids' eyes to see how well they can see....? The success of correction is pretty good for this!