The BDI-3 milestones are not based on any CDC guidelines. 

Rather, the milestones are based on the most robust State Standards (including Head Start), most current research in early childhood development [adaptive, SEL (from CASEL), motor, communication, and cognitive], other early childhood development tests on the market, and input from “expert” consultants working in those respective fields (e.g., school psychs, speech paths, etc.).

Those interested in reading the specific studies that were reviewed as part of the development process for BDI-3 should refer to the References section of the Examiner's Manual.