The parks aren't "packed," crowds are very manageable, but wait times are long without EP, but they have been historically practically every holiday weekend. Also, there is an Informer Meetup this Saturday, so lines will get even longer starting around 2-4pm. Last Saturday Spiderman got up to a 2hr wait without EP, the train was regularly at 90min. My recommendation would be get there at park open and leave when things got "extra."