Getting a read doesn't mean a heck of a lot, I'm afraid. Sure, they probably liked your pitch (logline, synopsis, etc.) but the actual script is what you have to sell. Hopefully your script is top notch. (Sadly, most newbie scripts are not in this category.) But the previous advice was on target. Don't wait around for the prodco to respond. It might take weeks or months, or they might never respond. Give 'em a call in a few weeks and see if they got your script. In the meantime, keep sending out those queries...and definitely get to work on your next script.
Good luck!