IFS is definitely a zero hour program, out of my flight of 24 only 5 or 6 of us had any previous flight time. 3 guys did wash out, but 2 of them simply didn't put in the study time on the ground so that they would be able to perform in the air. So while I think getting some flight time certainly helps, in this case 17 out of 18 folks with no flight time made it through. To me that means you aren't disadvantaged by showing up having never flown before. If you are willing to bust your ass while you're there you will be able to get by, even with zero hours.