Registration at Walt Disney World now occurs solely via video chat, no longer available at in-park Guest Relations locations. This can be completed up to 30 days before your visit.
This is a big change since before you could register via video chat, but you also had the opportunity to register in the parks by talking to a Cast Member in person.
If you don’t enroll in DAS before your park visit, you will now be directed to a location where you will still have a virtual chat on an iPad to determine eligibility.
So it is possible to do a same-day reservation, but you will be wasting precious park time to do it, which we obviously don’t recommend.