My DS started Waldorf a month before he turned 8 and it's been fantastic for him.
We moved him from public school because the social environment at the Waldorf school was so much better . .. much more open and he just fit in with the kids there, whereas he hadn't fit in at the public school and felt excluded.
Anyway, you might ask for some recommendations on books to learn a bit about the Waldorf approach. A lot will also depend on the school your kids would be going to.
But I wouldn't really worry about them starting later than other kids. For instance, my DS caught on extremely quickly with knitting, not as quickly with recorder, and is kind of ok with eurythmy (all special Waldorf subjects).
My DS is extremely creative and imaginative and loves working with his hands, so Waldorf was especially good for him, but I think any child can benefit from the approach.