I’m planning a summer trip with 6 straight days in the parks, including one day at Universal. First park day would be a Sat or Sun. I wanted to go to Universal day one for the small benefit in FPP reserving for the subsequent Disney days, but my understanding is that Universal is much more crowded on a weekend. So is it worth it to deal with larger Universal crowds to have the FPP scheduling advantage? What is that advantage worth in your experience?
I have no experience with summer crowds, but we do go every year during spring break so high crowds. Will you have Express passes at Universal? If so, crowd differences will really not be apparent day to day. Universal is just so much easier than WDW, I would go to Uni first to increase your chances of better FPP at WDW.
This may help you.
https://www.thedibb.co.uk/forums/showpost.php?p=10123554&postcount=1
I don’t know that I have seen a huge advantage beyond day 60+3 or 60+4 for FP selection and only then for SDD and FoP. I think everything else is fine at 60.