Multi won't help you in primary, which decides if you get jets or even continue with the program. While it couldn't hurt, an instrument rating and some real instrument flying will probably help you far more. Getting used to talking on the radio in a controlled environment and maintain basic air work should help your score immensely. Instrument flight will put you light years head of your peers in early stage RI's. But for the love of God, if you go down this route, don't ever let someone hear you bragging about your "experience." It will either show or it won't. What everyone is getting at is you will be starting over at square one with the Navy. Think of having prior flight time like being a good athlete in one sport and trying to learn a new one. Your speed, balance, hand/eye coordination, etc. that you honed in your last sport will help you in your new one, but at the end of the day you are still a basketball player trying to learn to play football. Half of doing well in flight school, and even the fleet, is based on your ability to study and know a lot of material COLD in a short amount of time. A photographic memory would probably be worth more than any amount of flight time you could get...