Bright suns, Lisa! Thanks for bringing your question to planDisney.
Meeting our favorite Characters in Disneyland Resort is one of the things my family loves best when we're visiting the parks. It's a magical experience to interact with the Characters you've loved and connected with onscreen in real life. So, I understand wanting to plan your visit around these special encounters. And while the Characters and their schedules change daily and are subject to cancelation, you can check for the most up-to-date information on the
Disneyland mobile app.
I currently don't see Darth Vader on the app's map, but you can typically find him near Star Wars Launch Bay in Tomorrowland at Disneyland Park. Recently, it's been in the first half of the day, while the
Disney Visa Cardmember Star Wars Opportunity has been in the afternoon. This is subject to change, so check the app on the day of your visit to better plan your day! But if you do see the Dark Lord, I'd protect yourself against the lure of the Dark Side.
Chewbacca is one of my favorites and my husband's too, and I can happily report we've encountered him numerous times over in Star Wars: Galaxy's Edge. We even got a quick picture. I see on the app's interactive map that he was found near the Millennium Falcon today, making several appearances throughout the day. Hopefully, Chewie is hanging out on Batuu when you're visiting that planet too!
To check for Character appearances, change the selection at the top of the app's map from "Attractions" to "Characters." This will bring up Mickey silhouette icons throughout the parks. Tap an icon to view which Character can be found in the area either in a Meet & Greet or roaming, as well as their anticipated appearance schedule. Training on the app like you would train to fly a Starship isn't strictly necessary, but playing around with it to find the different options is helpful ahead of your vacation. It will make everything that much easier.
May the Force be with you!
Elizabeth