When is the best time to start orthodontic treatment for children?

My child is in 6th grade in elementary school, and I heard that they need orthodontic treatment when they go to the dentist. Their teeth are a bit crooked, and their temporomandibular joint is also not in good condition... They said it would be better to do it now because if they grow up, they might need to extract teeth. I'm hesitant about it. Aside from the cost, once they get braces, their teeth will become more aligned... I asked around, and people said that braces are something you'll have to wear for life. If you don't wear them, your teeth will gradually become crooked again...

If I have to wear it anyway, is it better to delay a bit... or does delaying just make the problem worse? What's the best course of action in this situation?