They don't care how good you think you are. Don't say "But my next scene is where it gets really good!" They don't care. You need to be good on page one.
Many professional script readers will only read to page 20. It's not because they're lazy; it's because they don't need to. If you can't pull them in within the first 20 pages, then the rest of your script can't be that amazing. It's like, if you don't even dress fancy for your wedding, how could we expect you to dress fancy for work?
It doesn't matter if you're writing a comedy, a horror, a romance, a mystery, or porn. Your opening can and must be compelling.
Below is the opening scene from the movie Juno, as well as the corresponding pages from the award-winning screenplay.
Are you wondering HOW to write a kickass opening scene? I'm going to discuss it in tomorrow night's Write the Shit Out of a Story workshop!