I think one of the trickiest things you might run into at that age is getting composite scores. It seems some subtests might not be normed for very young students. Make certain that your tester is aware of your need for a test, with DYS-appropriate composite norms available for your child's age. I seem to remember that the WJ may had some issues here, with percentiles not available on composites up to the 145 minimum at age 4.
Yes - you are 100% correct on this we did run into issues with this exact issue on the WJ. It was still worth doing the testing as it was more or less at the end of the school year. We can see clearly a lot of progress and hopefully it will establish a baseline for future achievement testing every 2 years or so. (our tester is nice and fun too so DS4 had a good time doing this).
