We just did a trip a few weeks ago and I think we timed it just about perfectly. We went from May 2 - May 5 (park days the 2nd, 3rd, and 5th). Spring breakers were gone but the summer crowds hadn't hit yet. Wait times were very reasonable and while I wouldn't say the park was empty, it was definitely far from packed. Plus the weather was fantastic with highs in the uppers 60s to maybe 70. Wouldn't hesitate to go again in early May.