Since you are homeschooling, I see no reason in the world to test if they don't have the capasity to do the SB-IV. In other words, there is no point in having her do the WPPSI as it won't give you the info you need. If they can't do a SB-IV, I would make the appointment for the week after her 6th birthday.
I totally agree with Grinity. We've had the K-12 Peabody administered in our home for $50 and that was extremely informative. Locally testing for us is sky high, so we've never done a full round. But now that we have 4 pieces of achievement data we have a good feel for where we're at. I think my child *could* be at DYS level, but it's not worth $2000 for me to find out for sure since he doesn't show any 2E tendencies and $2000 goes a LONG way towards enrichment for him.
At the very least, I'd definitely wait until she's old enough to get the data you really want! Good luck! :-)
