Parents with daughters!

I need some advice, I didn't have my mom on learning properly about the right ages to start wearing bras, start shaving, or anything for that matter. Therefore, I'm unsure for my daughter, she will be 8 this year & I'm wondering if now is an okay time to introduce her to training bras. I only ask because her "girls" in certain shirts show more than what they do in others. So is 8 an appropriate age to start her on training bras or do I get her under shirts? She's my first born & I'm learning as I go, there's still lots I'll need to learn I'm sure especially since I'm having trouble over a training bra 🤦🏻‍♀️ lord help me.