The touted righty will get the ball in the Astros' Sunday exhibition game against the Rojos del Aguilla de Veracruz of the Mexican League.
"I've dreamed about it a lot, just pitching in the Majors, and especially here," said Appel. "Being able to go out on a big league mound and put on an Astros uniform will really be a dream come true, and I'll cherish it forever."
Appel hasn't pitched in many games this spring while recovering from a January appendectomy. He made his big league Spring Training debut in Wednesday's win over the Mets and is still working to be at full strength for Opening Day at his Minor League destination.
"Strength is the biggest thing, just getting that back," Appel said. "It all works together -- leg strength, core strength and back strength. From there, it's about establishing timing and pitch location, refining my offspeed pitches."
Due to his limited work, the staff will have a close eye on Appel in his homecoming start. The Stanford product said the goal is to pitch three innings.
"I'll take it as it goes in the first, and see how it progresses from there," he said. "They don't want to put me in a taxing situation at all. Hopefully, I can make it easy for them and compete and get guys out."
Appel hopes he can toss a few frames for the sake of his cheering section, which he said will number between 15 and 20.
"It'll be friends and parents, aunts and uncles, and people I knew here," he said. "It's definitely a big moment for me."
Alyson Footer is a national correspondent for MLB.com. Follow her on Twitter @alysonfooter. Chris Abshire is a contributor to MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.