Hey, I am in IFS right now, and You do have to do it after OCS (at least for the Navy, don't know about the Marine Corps but would be willing to bet its the same) and before you can class up for API. You cannot do it if you have a private pilot certificate or any solo or cross country solo time, I believe. The Navy/Marine Corps will spend the @$3,500 on you to see if you can hack it in the air because per student API costs around $16K and Primary costs over $140K. In short, a $3,500 insurance policy that acts as both a learning tool and screening program is better than just dropping well over 100K. By the way, these figures were quoted to us at the welcome to IFS brief. IFS is either a really awesome time for those of us who don't have any previous experience and end up really enjoying it, but I have heard of some people who go up and do stalls for the first time and just freak out and end up DOR-ing or getting PRBed because the CFI screens them out for being unsafe or unteachable. That sucks for them, but it is good in the end because who wants SNAs in training that would rather not be there? I know that I am very thankful for my SNA spot and I know that a lot of people out there would just absolutely do just about anything to be in our shoes.