You can pick up your package tickets up to 3 days early from Guest Relations which is adjacent to the theme park entrances. Also can pick up at GR at DTD. They will ask for your package reservation info and photo ID. If you're using your tickets that Saturday you can't schedule FP+ for the day until you've received the tickets. If your room-only and package resort are the same, it's possible to pick up the tickets there, but don't be disappointed if you don't encounter someone who knows how to handle that situation. Park Guest Relations is the place with CMs who are familiar and trained in this procedure.
You can't combine two tickets for the upgrade to any single ticket. I'm confident you'll be able to get your tickets on Saturday. People post here all the time about their success, and it is a legit DisneyWorld procedure. But note that any WDW rep you speak to on the phone will tell you the early pickup can't be done. They're trained to say that and it causes confusion for folks who write here. See Cheshire Figment's ticket sticky at the top of this forum, post 15-I,
Picking up Package Tickets Prior To Start Of Package. It's from 2013 but what it says is current except for no KTTW cards any more.
http://www.disboards.com/threads/everything-about-wdw-tickets.1452684/