It depends on what profile you have got? And whether you are really interested in Air Force??
Look at the future growth prospects if you join now with Class 12 qualification. Evaluate and then decide. Definitely perks will be good, but in the long run, you will be just a 12 pass out. But if your love for being in the Defence overrides everything else, then it is another thing.
Engineering in itself is very lucrative. Sure you cannot join later on after you complete your degree? Or maybe take a transfer?? Does corporate life also lure you?
My friend, these are some of the questions that you alone can answer before you take any decision! Good luck!