What are the required waiting periods for WGIs, and when do the WGI waiting periods begin?
See the fact sheet on General Schedule Within-Grade Increases for the required waiting periods for advancement to the next higher step of a GS grade for employees with a scheduled tour of duty. (See 5 CFR 531.405(a)(2) for the required waiting periods for employees without a scheduled tour of duty.)
A WGI waiting period begins upon (1) first appointment in the Federal service, (2) receiving an "equivalent increase," or (3) after a period of nonpay status and/or a break in service in excess of 52 calendar weeks.
Fact sheet available at http://www.opm.gov/oca/pay/html/wgifact.asp