When it can live outside of another person’s body. Just like how no matter how much I want a kidney that you promised me if you decide that you are no longer willing to undergo surgery to give it to me, even if I’m already knocked out to receive it, you can back out. You are the ultimate master of your body, but so is everyone else.
Okay, so then you believe that a person has rights when they can survive outside of the woman. So then the humanity of a fetus depends on location of the mother because in some countries the fetus can be born much earlier due to medical technology. That is not a logical stance.
I believe that the fetus’s right to live doesn’t supersede a person’s right to not be pregnant. That is a logical and consistent stance.