Two things:
1. Unless it's changed since I went through, it doesn't really matter what color your backpack is for I-Day. I wouldn't bring something obnoxiously colored, but the one you posted a picture of should be fine for the purpose of I-Day. Just go by whatever guidance they give you in your appointee booklet.
2. I'm attaching the guidance for school year backpacks from our regulations below. I would say that backpack is probably outside of the regs just because all of the white on the straps. I encourage anyone who wants to use their own backpack, however, to do so. I hated the issued backpacks and spending a little money on a sturdier bag I preferred was one of the best purchases I made last year.
"Issued blue USAFA or plain, solid black backpacks may be carried in left hand, over left or both shoulders while in AF blue uniform. Backpacks are not to be worn over both shoulders while in service dress uniform or parade uniform. Backpacks may be carried in left hand, over left or both shoulders while in ABUs. Issued blue USAFA, plain, solid black, olive drab, or sage green backpacks may be carried in left hand, over left or both shoulders while in ABUs. No other colors or any color combination of backpacks carried. Issued blue USAFA backpack is not to be altered in appearance (e.g., affixing patches or pins, etc.). Bags or backpacks will not be worn with shoulder straps across chest in any uniform combination. Conservative logo authorized."
