Enemy firing bullets at player

I finished the tutorial and began working to create my first game. I have run into a dilemma, though. I am currently having my enemy fire objects at me when the enemy is visible on-screen. However, the enemy is firing the objects in a constant stream. Instead, I want the enemy to fire an object, pause for a half second, and then fire again. What is the best way to do this? Thanks!

Use every X seconds event.

Thank you for your help; I used your suggestion and it worked.