Sounds like a very nice tester. My DS5 took the SB-V when he was 4.1, and he thought it was really fun. I would take the psychologist up on the offer to do the testing on different days, though, especially if your son hasn't had testing before. The SB-V can vary quite a bit in length. If I remember correctly, it took DS about 1.5 hours? But other kids have taken longer.