No, you should start applying the second you are eligible. Don't wait until you have been a lineholder at your regional. First of all, there is no guarantee that you'd get hired by the first (or fifth, or tenth) unit you interview with, let alone getting that interview in the first place so you want to start as young as possible. I don't know if you realize it yet, but those slots are extremely competitive, esp the fighters. Plus I think most fighter squadrons only interview once a year. And also, for Guard I think it may take up to two years between the time you interview and the time you actually go to UPT. So by the time you enter training, you might already be a captain! Which is still fine I think but it doesn't go along with your plan. I say get all the tests done and get your package together during college, and then start sending them out as soon as you get your degree.