You can start wearing a bra when you can do the pencil test.
Lift up your breast and put a pencil horizontally underneath it.
Then lower your breast over the pencil. If the pencil doesn't fall away, you can wear a bra.
But if I were you I would not bother. When you start wearing, the support tissue under the skin of your breasts can not develop, and your breast will be sagging all your life. Ligaments is the name of the natural support tissue.
I prefer the gentle jiggle and bounce of my breasts.

You can start wearing a bra when you can do the pencil test.
Lift up your breast and put a pencil horizontally underneath it.
Then lower your breast over the pencil. If the pencil doesn't fall away, you can wear a bra.
But if I were you I would not bother. When you start wearing, the support tissue under the skin of your breasts can not develop, and your breast will be sagging all your life. Ligaments is the name of the natural support tissue.
I prefer the gentle jiggle and bounce of my breasts.

Hadn't heard of this. I tried the pencil test. Not surprisingly the pencil stayed in place under my right breast, the larger of the two, but not under the left breast.

But I am not interested in wearing a bra. I only put on my open-cup bra when I am having a nipple orgasm session. Having my breasts feel larger and fuller enhances my pleasure.

I've known grown women who couldn't pass the pencil test, even though they were already at least D cups, because their girls defy gravity!! Or, they have the kind I wish I had, that just flow smoothly from top to bottom like there's just a nice, beautiful lump under my skin, kinda like a baseball pitcher's mound.