Yes. You can take the older preschool level of WPPSI-IV at age 4-0. You can take the WISC-IV or -V at age 6-0. The SBV and WJIIICOG can be administered beginning from age 2 (but I wouldn't put too much weight in anything administered at that young age). There have been various threads and posts about the value of achievement testing for four-year-olds. You can obtain some information from the WIAT-III, KTEA-II or -III, and WJIIIACH or IV, but all have significant limitations for preschoolers.
As long as you have realistic expectations for testing results, there is little harm in them, and some potential benefit: IQ numbers are notoriously unstable beneath the age of nine or so (for many reasons, not least of which is the unpredictability of small children in attending and complying with on-demand tasks).
