I know exactly where and what you're talking about. I dug out my trusty Dover Edition and had a peak.
This is a very beautiful sonata. I've been working on, for many years now, his very beautiful last one in B-flat, and I've read through (only once) the one you're working on for real.
Anyway back to your problem. Couple of things to try.
1) Balance the chord toward the bottom.
By doing this, the rest of the fingers will fill in naturally. You can use the get-ready position, but plan to land with the outside of the hand. Also don't try so hard. Sometimes by working too hard at something it never happens.
2) Try the exaggeration method.
Don't do this just before a recital because you'll confuse the snots out of yourself... Trust me...
Try jumping to the chord, but instead of playing it where it should be, play it lower. Do this a few times, maybe five or ten. When you go back and try the correct version, your mind will be tricked into thinking that the chord is a lot closer than it really is.
Anyway I hope this helps, have a lot of fun, and I hope you're enjoying your time with Mr. Schubert.