J.P.
My daughter got her braces and expander put in at 7, top teeth only. She had already lost most of her baby teeth by then (no extractions done). Her bite was off and with the baby teeth coming out so quick I was concerned about overcrowding (my SS had teeth coming in above his others). Her cusbids/canine are taking forever to come down (one is almost in and the other is on its way, her orthodontist always shows me the x-rays).
Right now her top braces are holding places for the cusbid/canine teeth since her second molars are coming through and we can see her wisdom teeth coming down in the x-rays. My daughter is only 9 and her teeth are way ahead of where they should be so this was the best options for us. I also noticed that her teeth moved quick and we only needed the expander for a few months. I don’t know if that is because she is young or genetics.
Having an expander is not a big deal, they get used to it quick and it shouldn’t interfere with sports. They just have a lisp until they adjust to it being in their mouth. IMO, I think it would be better to have the expander while they are young.