We went in Feb 2020 when they were 10 and 13, and then we did Universal a few weeks ago at 11 and 14. I'm so glad we waited until this age. They are old enough to go all day and not get tired and whiny, they loved all the bigger rides, and they loved both places. They liked the organization and food better in Disney, and the rides better at Universal (they seriously need to figure out their food and water situation). I think waiting 4-5 years is great advice. We also went before it got *super* crowded, and I can't imagine going with more people than were there (Universal) at the beginning of June. I think it would be horribly miserable. I like the October time frame as well, although February was great (Disney).