For those unfamiliar, Schelling points are points that people naturally converge to without any communication. An example would be two people being told to meet each other in New York, if you go to Grand Central Station or the Empire State Building at noon, you have a decent chance of meeting someone given that same instruction. This even occurs in nature, as butterflies will all travel to the highest points of local elevation to find mates.
In theories of when a fetus becomes a person, two options become immediately obvious; conception, and birth. There are others, the Biblical concept of quickening, the point of fetus viability, that many people have used.
I'd like to hear people's ideas, are there any others that I'm missing? What are the best arguments for each? How would these translate to an AI or sufficiently advanced animal gaining personhood?