From my experience, I received an automated past due notice about 3 months after I left. I followed up with accounts receivables and waited another 3 months while they confirmed the amount. Once it was confirmed, I wrote a check for the amount less what was withheld in taxes. They're estimating 8 weeks on a corrected W2. That's been with follow-up emails and check ins every 1-2 weeks.

I would hold the money in high-interest savings, and if you do leave, reach out sooner rather than later to start the process. envoy.receivables at aa.com