I'm also switching from 0-1 to EB1-A. Premium processing only applies to the I-140 part (qualification for the category.) The I-485 adjustment of status still takes at least three months to be processed before you get the actual green card. The big advantage of the EB1 here is that I don't have to wait 9 months for the labor certification. Hopefully I'll get my advance parole a little sooner so I can travel again as having applied for the AOS I'm unable to re-enter the country on my O-1.