My cousin books trips for Disney through a third-party affiliated company and she knows WDW front and back. Historically speaking, if you're looking for smaller crowds, the best time to go to WDW has almost always been the 3-week stretch that starts with the Monday after Thanksgiving and runs through about December 15. You get in just after the Thanksgiving week crowds leave and before the massive Christmas crowds (that stretch from Dec. 14/15-25/26 is usually the WORST time to visit re: crowd size).Wow, I wonder how crazy the lines and traffic are going to be for this? I will be hitting up the outfitters for costumes first thing
When I last talked to her over the holidays, we got to discussing this very thing because my wife and I want to try to get down there this year (had to cancel a trip we booked in 2017 and we've wanted to go back as soon as possible) and I want to allow for at least a day or two just to be spent in Galaxy's Edge. She said that Galaxy's Edge opening in the fall will almost certainly blow the old "ideal times" schedule completely out of the water. I'll have to check with her again to see if she's heard any updates on what Disney is expecting, but I'd have to imagine they've planned well for it and will have various ways to minimize the impact of the crowds.
I've just come to terms with the idea that it's going to be busier than hell and it will likely be that way for the better part of the next five years (maybe more), and it's going to be part of the experience. It's safe to say that demand is going to be unlike anything that's opened there before, probably even bigger than anything Universal dealt with when Wizarding World of Harry Potter opened.
Either way, I can't wait to see it, whether I get there later this year or sometime in 2020 or 2021. I'm 43 years old and Star Wars was the first thing I really remember falling in love with as a fan. The new films and finally digging into the expanded universe stuff has allowed me to appreciate it all even more. Not ashamed to say the first time I walk into that place, it's probably going to get pretty dusty.