At what point do you know what someones sexuality is?

Do you mean "Sexual Orientation"? well first off someone doesn't exactly have to have sexual acts to determine their own preferences. They're preferences. You could be attracted to both sexes but only act according to one. So my answer is that sexual orientation is determined at the very moment the person in question starts to feel any attraction what-so-ever to either sex. Of course the orientation can change from then on out, happens all the time.

People other than that person may not always know which sexes the person in question is attracted to unless they give clear indicators. So knowing someone's orientation is not always an easy task. The moment that person has a preference is tricky too, but I can tell you each persons "time" is different.

I didn't know what gay really meant until I was in my teens but I do have memories as far back at the age of 6 that make it certain my sexuality was already set back then.

I knew when I was 11. Long before I knew what sex was. Before I even really began puberty, actually. But if you're asking when you know what someone else's sexuality is, you know when they tell you.

I was pretty sure I liked girls at about age 8 or 10. I'm guessing that's the age for most people.

Probably when they straight up tell it to you. It's complicated for some people, whether they're curious, bi, or 100% straight or gay, people you'd never expect to be actually are.

about mid puberty they have it figured out.

When you catch them in the barn with a goat.

once that person tells you or anounces it to you or others~~ you cant really tell.. ~~

YOU can't. They can.