I think Mistermoe (where on earth did that nickname come from!?) put it quite succinctly. I think some music on a smaller scale would be more beneficial to you at this moment. I, personally, don't care for the 3rd sonata. I played it once in my lifetime. For my graduate programme. It just rambles on and on. The scherzo is lovely, though. Anyway, that said, go for the first ballade if you want. and the first scherzo, as well. ONe of the bigger nocturnes. You have lots of time to learn that 3rd sonata. And definitely, as Mr. Moe said, wander into the classical repertoire as well as the contemporary field.
I have to agree that most of the 3rd sonata are far from Chopin's best work, but that finale is SO much fun to play . Its as finale as a finale can get.