We let our kids brush in the morning and we brush at night, so they have the time to build the skill but also we have peace of mind knowing they're getting 1 good brushing in per day. My 9.5 year old can do it mostly independently now, and we'll transition to that child brushing only around 10.

For all elementary aged kids, we've found the Fairly True Stories (4 books) to be so great for read aloud! They are re-tellings of classic fairytales, but have great fun plots my kids all loved.

For K-2:
Magic treehouse, dragon masters, A-Z mysteries, My Father's Dragon series, Stuart Little

For 3-5:
Mysterious Benedict Society, Gary Paulson Books, Judy Blume Fudge Series

3 summer kiddos here, and I'm happy I waited to send them. They were ready academically at 5, but the school day is long and I was grateful to be able to give them an extra year to learn through play and develop a bit more maturity. We were in a position where doing that didn't create a huge burden for our family, but if it had I may have done things differently.