On most WJ IV™ tests, the first page after the tab in the item book provides special instructions or procedures to be followed and indicates where to begin a test

The starting points located on the Suggested Starting Points table are determined by an estimate of the individual's present level of achievement/ability, rather than by their actual age or grade placement. Suggested starting points, coupled with basals and ceiling levels, help to reduce unneeded testing time. 

More information regarding Suggested Starting Points can be found in Chapter 3: General Administration and Scoring Procedures of the Examiner's Manual.