6 years old. I had one set done with wax when I was 17. I was told to apply wax 2 times a week and not wash for 2 months. I did what I was told and my hair melted off my scalp. I mean it. When I finally washed them, the pressure from the water just peeled the hair off my head. I didn't even have to touch it. So I started my next set after shaving my head and starting from scratch.
This set I back combed one or 2, TnR'd a few, and just let the majority of them do what they wanted. I used bands for about a week, and it was just pulling hair out left and right so I stopped that. I palm rolled 4-5 (check my video on what palm rolling does to your roots).
6 years later, I can say that I did almost every method that people try, minus crocheting. I even interlocked one or 2 and can attest to the damage that does. I don't want to cut my hair ever again, so I am dealing with the recovery stages of all of the processes. It's been long and grueling, but totally worth keeping my locks.
It's better for them to be all different sizes. It layers them and fills in gaps. Plus it just looks more organic