Origin of warmup
Examples from the Web for warmup
The first concert had been headlined by Thin Lizzy, with a then-little-known band named U2 as the warmup act.Eminem Rocks Ireland: Slane Castle’s Latest Legendary Performer|Michael Daly|August 20, 2013|DAILY BEAST
Eastwood, who was supposed to be the warmup act for Marco Rubio introducing Romney, wound up with marquee billing.
“The vice president and I are the warmup acts today,” the president joked.
Apparently that topless shot in Vanity Fair a couple years ago was just a warmup.
This was the warmup for the original Compassionate Conservative—the one who campaigned as a different kind of Republican.