"In fact their first combat mission was not until the Sicilian invasion of July 1943 to attack the small island of Pantelleria in the Mediterranean Sea between Sicily and Tunisia. This is at least a year into the ETO operations, which I would not call the very early part of the war, but rather the latter half."
Not really. The invasion of Sicily was one of the first ETO operations, if not the first.
"The invasion of Sicily was one of the first ETO operations, if not the first."
ETO was formed up and began deploying troops in the middle of 1942. Sicily was an invasion force, but US Army European operations were well underway for quite some time before the first invasion began.