Just wanted to "pop in" and say that I spoke with Art Reed on the phone yesterday. (I purchased his DVD series for Algebra 1/2.)
His advice was to start testing with Test 1. The parent should score the test like "Atilla the Hun" (his exact words) -- meaning no partial credit for forgetting to reduce fractions, etc. Review the missed problems. In a day or two, do Test 2...and so on until the student scores less than 80%. This is the point at which you start in Saxon.
He was WONDERFUL!! You can call or email any time with questions, concerns, etc. and he answers each and every one in person within 24 hours.