You have to have the available prospect budget to at least offer the picks their demands if you want type D comp. If your draft is still a few days away the IFA will likely be gone by then it seems, especially since some of the guys you draft will take a week to decide whether to sign or not.
At any rate, there's always a risk they will sign. The guys who say they're unlikely to sign rarely do, the guys who are weighing other sports sometimes do, the guys wanting to be taken high usually do, and the guys who say they will sign always sign. For the guys in the two middle groups, most times they reject the initial offer and then request more money which means, once they reject you can get Type D comp, but their reply can take up to a week--probably too long for you to still get the IFA you want as mentioned above. From my limited experience anyway.