Then this new document is for you! The DC Budget Process Explained (PDF) contains links to find budget-related documents (CSFL, budget books, revenue estimates) intervention points in the process along with what advocates can do.
Note: The document is legal size but can be printed on either letter or legal paper.
A special thanks to T.J. Sutcliffe and Marina Streznewski for reviewing the document and, as always, making it better.