We flew at 12 weeks, and it was logistically really easy, except for all of the gear we were toting!
That said, I'd try to wait until baby has had the 8 week shots. Contrary to what PP said about shots having nothing to do with "most of the illnesses floating around", pertussis in particular is a real risk. Could you push back your trip a hair?
I would also factor in flight length. A short flight is no big deal, but longer ones could be. How will you negotiate getting to the bathroom? (or not?) Eating/drinking, if you want to do that? Not saying everything is difficult, just to be thinking about how it will be as one person with one pair of hands that happen to be full of baby!
You also have to get through security by yourself, which could be a little tricky if you are planning to gate check your stroller. I distinctly remember my poor husband trying to fish all of our gear off of the xray belt a la the I Love Lucy episode with the chocolates--stuff kept a-comin (stroller! carseat! Diaper bag! other extraneous crap!), and he kept a-grabbin, while I had gotten pulled aside for an extra security check and was not allowed to help him. Pure comedy--I'm trying to imagine this scene if you are by yourself.
It's all doable, but if you are a FTM, some moments may be particularly lively.
Good luck!