The link you sent is only for AC21 provision. It's not after GC.
After GC, it's still a grey area. That's where you go with attorney's advice. 6-12 months is considered enough time by most attorneys.
If you leave as soon as you receive your GC then you need to substantiate it to USCIS during N-400 if a need arises. So staying with your employer at least for 6 months is sorta future proof. Leaving earlier than that, you need to be prepared if USCIS asks any questions during N-400.
https://www.murthy.com/2019/07/29/ch...ed-green-card/
And, several others give you the same advice. My attorney recommends at least 6 months.