Putting aside infant Baptism, I see no reason why #3 and #4 must be separate events. The Ethiopian eunuch (full account, Acts 8:26-40) appears to have been taught (by Philip) about Jesus and Baptism at the same time - he says, “Look, here is water. What can stand in the way of my being baptized?” His desire came immediately after hearing Philip’s teaching. Had there been no water available, and they had been beset by brigands and killed, we could assume the eunuch had desired Baptism.
But suppose Philip (for some strange reason) been more restrained in his teaching and held back on the concept of Baptism. The eunuch declared, “I believe in Jesus and will do everything he wants me to do.” Then the brigands come and kill them all. This is at least an implicit desire for Baptism. We cannot know for sure how he would have reacted if Philip had explained it - maybe he would have said, “that’s stupid” and rejected it. But GOD knows how he would have reacted.
Let me just clarify something. Assuming that a person lives the most moral life, invincible ignorance allows for salvation when a person dies between points 1 and 2
No, invincible ignorance has nothing to do with such things.
Invincible ignorance is the Catholic teaching that we cannot be held accountable for a sin (either of commission or omission) that we did not have any reasonable opportunity to know was a sin (ie, we cannot sin accidentally, without consent). That is a VERY broad idea, which happens to ALSO apply (in a tiny fraction of the situations) to people who are held innocent from sin of disbelief because they did not properly know correct belief (such as righteous pagans).
Suppose you’re on a game-show, and you ask a contestant to define “invincible ignorance.” If they start out, “The teaching that people who have not had the opportunity to know the Gospel…” then BZZZZ you hit the buzzer and they are disqualified. That is one very narrow and trivial application of the concept. It is not at all, in any way, shape, or form, what the doctrine actually means. The doctrine is usually applies to Catholics.