My first answer to your question is "When you feel you have sufficient coping skills to adequately reverse growing episodes." Of course the ability to reverse episodes can sometimes be very hard, or impossible, but it must be a lot more than "rarely" or "occasionally". Study or work will be stressful. It will be. How has your stress tolerance been, in recent months?

I think a major barrier for people on disability going back to work, even part-time, is fear of either losing disability payments or otherwise not being able to pay bills...if the effort backfires. That's a sad fact in life for many of us. Those who have nothing to lose? Definitely go for it! Those with iffy situations, I'd seriously do some planning for backup strategies. And again, first hone your coping skills.

Many people try volunteering before jumping into higher responsibility situations. I realize volunteering itself allows an easy out. Having a major responsibility does provide extra incentive to stick with something, but unfortunately that pressure isn't always stronger than the illness. There are jobs out there that pay a bit, yet do offer accommodations and flexibility. They might be the best to try first. If you choose the studying route, I strongly recommend starting with only one course. Beware of signing up for 12 credits (or even 6) from the get go. Some years back, I took some online courses for credit, but only one course per semester. The fact they were online (and not face-to-face) also helped ensure greater success. A commute, itself, can be a big challenge/stressor. How comfortable are you at driving or taking public transportation yourself? Sitting amongst strangers, often people your son's age? Going somewhere "every once in a while" is not the same as the pressure of going twice (or more) per week. A commute of just 5 miles is different than 10 and up, for some.

If anything I wrote discourages you, please don't let it. Rather see it as "next baby steps" in preparation for the future.