The book skips the first 20 weeks for the boys but covers those activities for the girls (around the end of the book). So I'd suggest reading the girl circle and then coming back to the boys circle... I've absolutely loved that book and I've been trying to incorporate some of the ideas in games with my son.
That said, do keep in mind that despite being from 3 to 7, his son is actually 3 years old and 10 months when he started (and I think the same for the daughter, I forgot). Personally, I've noticed that my just turned 3 years old son is not developmentally ready for a lot of the activities yet (but he's been surprisingly good at other activities), so I do think that you need to adapt depending on the children you try this on.
That said, do keep in mind that despite being from 3 to 7, his son is actually 3 years old and 10 months when he started (and I think the same for the daughter, I forgot). Personally, I've noticed that my just turned 3 years old son is not developmentally ready for a lot of the activities yet (but he's been surprisingly good at other activities), so I do think that you need to adapt depending on the children you try this on.