There are a lot of people on r/USCIS on Reddit that say the chat agent told them their interview was waived well before (months) a decision is made. I'm not sure I really trust anything that the contractors in Emma are saying.
OP, I think it's 24 months total. Anecdotally, lots of August/September 2021 cases are being decided right now, obviously this is FO dependent. Also, please fill out your timeline.