I don’t even know if that’s possible. The school you would defer might not accept that offer; they may want you to re-apply for that term that you would be starting there. The school I’m at goes through phases: some years they have tons of applicants, and some years they have very few. It really all depends. So lets just say they accepted you this year out of a small pool (not saying you’re not qualified, I’m just giving you a hypothetical). But maybe next year (the year you would want to start there), they had a huge surge of qualified candidates. They only have room for so many grad students, so would it really be fair to keep you when maybe there is someone more qualified for a spot? I don’t know what field you are in, in the sciences it is really cut throat. I would also recommend to you to go to the school where you have guaranteed funding, even if just for a year. If you do well your first year, you could probably easily get that money again.