We joined an accelerator when we were quite early stage - no product, just a concept, a vision and a nice slide deck. Looking back on that experience, I think rightly choosing the timing you join an accelerator is a critical element. Join too early and you will not be able to leverage much. Join too late and you might just waste your time. In our case, the biggest benefit we got was to network with other startups from the cohort, even building some key partnerships that helped us move forward. And the exposition we got after winning the pitch competition at the graduation ceremony.
We became a part of a local one recently and the jury is still out. I like having people to check in with about my progress, the additional financial support is nice, but I'm not sure if I'd be a part of it if we had to give up any equity.