I think a better answer would be - go and see your AFCO and discuss your options and the best timing. You say you are in the middle of your degree, but we are at the start of the academic year, so you are presumably either entering your second year, or your third and final year?
My understanding is that OASC will not defer your entry if you are a second year, for what is effectively nearly two years, or at least 18 months by the time the selection process is finished. Even if they did offer you a deferred place, they would rescind it at any point that they got a better candidate - unless of course you are going for a final year cadetship?
Your best timing option seems to be to start the application process at the start of your third year, which gives enough flexibility for a few delays in the process to occur and still give you an IOT date after graduation. If you hit the process when everything is moving smoothly and you pass everything by January/February of your third year, then they will defer your IOT date until after your graduation from Uni.