The corn maze is open 10am to 5pm Mon-Sat for regular business and then for the seasonal activities, 7:30pm to 10:30pm Fri and Sat for the haunted corn maze. You can get a discount on tickets if you bring a canned food donation.
For kids under 6, day time is better.
Last year we took our son there to walk in the "haunted" corn maze. They decorate the corn field with skeletons, headstones, and spiders (in addition to the real ones!) and have scary sounds. Our son was too young for the night-time experience, but he still had fun during the day. Parents may be underwhelmed, but the kids enjoyed it. It's a trek out there-- 45 minutes from Las Vegas-- but the Corn Maze has a gas station and convenience store right next to it so you can get lunch and use the potty.