We use Math U See. And I agree, if you want to jump in, PreAlgebra is a good point because you’re done with the basics (add, subtract, multiply, divide, decimals, percents, fractions) that MUS spreads out in a nontraditional order. My oldest is in Algebra 1 this year and started with Alpha in 3rd grade, the rest of the kids have done MUS all the way through, currently two in Epsilon, one in Gamma, one in Alpha, one playing with Primer, and a few too young to start yet.
Saxon has a lot of review problems. One option with a print curriculum that isn’t there with a computer based one is not having them do all the review problems, so telling them to do odd problems only, for example.