1. The TN for founders is problematic and risky. The better (but not necessarily easier to get) are the E-1, E-2, and O-1 visa classification and the IEP (but the IEP program isn't really working). 2. Legally, there's no requirement to stay any minimum amount of time. 3. Even if the termination happens before the I-485 has been pending for 6 months, there are ways to keep it alive (but this question requires a call because it's a bit complicated/nuanced).