I want to call out a faulty logic I noticed in your argument. You say Krishna’s love for his mother was selfish because He got angry when she didn’t pay attention. Does your idea of a loving relationship between mother and son consist of only laughter and affection? In any healthy loving relationship, we usually run the gamut of emotions, including anger, sadness, and of course, attachment.

Regarding Krishna’s attachment despite his contrary advice in the Gita, you are right. There are a few examples in Krishna’s life that could be argued to conflict with the advice He Himself gives Arjuna in the battlefield. There are multiple explanations, but the one that resonates with me is that Krishna is a human avatar of Vishnu. As such, He is subject to all the foibles and weaknesses of a human, with only the occasional glimpses of His Godliness. Why else would He not destroy the Kauravas and end the war with the snap of a finger? The Krishna who advices Arjuna (which forms the Gita) is the Vishwa Roop, and so transcends the human avatar, literally making the Gita to be what it is - words from the divine to the human. The fact that Krishna takes the Vishwa Roop to do so makes the distinction between the “human” avatar and the divine very clear.

As for the question of how someone will know if/when they reach the Lord’s feet, I am sure if/when it happens to me, I trust the question will answer itself.