Hi Jean Ann,
You should be fine to pick up your Epcot ticket either late on June 19 or on the day of your visit.
Epcot has two Guest Relations locations, one at the front of the park on the far right of the entrance area, and one at the International Gateway entrance. Please note that you will need to park (and pay the parking fee if you are not staying in a Walt Disney World resort) and pass through security to reach the one at the front entrance, so it may be inconvenient to go the day before.
You should only need to go to the designated Guest Relations if you are picking up a ticket that already has been set aside for you by the conference. If you are simply purchasing a ticket, you can do that at any ticket window at either entrance. If you are staying in a Walt Disney World resort, you also should be able to purchase a ticket at the front desk of your resort.
There usually isn't a long wait at Guest Relations or the ticket windows, though the lines may be longer near opening time. So if you can get your ticket in advance, you'll be able to get inside and start your fun-filled day sooner.
I love a day at Epcot, enjoying the
rides and attractions and eating my way around the World Showcase. I've attached a video from some of my Disney Parks Moms Panel friends to help you with ideas for ways to spend your time.
Thanks for your question, Jean Ann, and enjoy Epcot!
Wilma