I am no expert, so you'll want other input too. However, my DD6 was tested in the WPPSI 1.5 years ago, and then we had her tested with the WISC right after she turned six (hoping to get her into am amazing gifted school). The benefit of the WISC is that you can calculate GAI (I don't think WPPSI or SB-5 have that capability). If your school will accept GAI, it can be a lot higher than FSIQ scores for these highly gifted kids.
So for me, it was definitely worth testing her again as a 6-year old on the WISC because her 139 FSIQ WPPSI score missed the application requirement by 1 point, but her 144 GAI WISC score surpassed it. Since you can't test them more than once/year, I might wait till March if I were in your shoes. Again, I am no expert, so please wait to hear from others on the forum.
