Olds was promoted to first lieutenant on December 1, 1943. In early 1944 he became part of the cadre assigned to build up the newly activated 434th Fighter Squadron and its parent 479th Fighter Group, based at Lomita, California. Olds logged 650 hours of flying time during training, including 250 hours in the P-38 Lightning, as the 479th built its proficiency as a combat group. It departed the Los Angeles area on April 15 for Camp Kilmer, New Jersey, and shipped aboard the USS "Argentina" for Europe on May 3. The 479th arrived in Scotland on May 14, 1944, and entrained for RAF Wattisham, England, where it arrived the next day.