Started around 11 yrs with mine - just when it happened..
Was at the 40+kg mark...
Safety safety and safety...
I went with good impact vest with moderate floatation but not PFD level, helmet, and ability to swim well - did nippers and some squad training.
The main aspect which will come up is reach when they are smaller, so the shorter the throw for depower the better. The harness style which has comfort + a smaller hook. I also ended up making the chicken loop smaller. We started on a seat but he soon made up his mind he wanted a waist harness. Bought a 6m which went well for the first 3-4 kids who have learned on it.
Masses of beach work, a lot of shallow water work, then when he was getting on the board - he did a couple of lessons. I wanted him to get another take on safety etc... In retrospect I probably held him back as I went safety first...
The big leap came when he did a grom fest with Kitethrills - Andy Yates put the pedal on the metal for 3 days - shortly after that what Puetz said...
He is working on his latest video - here is last years....
If you have as much fun as I did helping your kid - you will have a blast..
Cheers
AP