brabus speaks truth!
My take: No point in waiting, especially with the statistical norm of folks trying multiple times and/or with multiple units (enlisted or not) before eventually getting hired. As far as being enlisted first, I'd say there's more truth to "risky" but I'd be hard pressed to put my name under calling it "highly successful" when it comes to hiring boards. The one thing that is known but isn't talked about a lot is that more often than not, enlisted members would still have to be relatively competitive against the street applicant pool if they are to be considered. Being competitive AND well known as a good dude in the unit will work well in your favor. However keep in mind that if you are not viewed as one of their kick ass troops, no amount of time in the unit will get you hired with the squadron. This is a common misconception and what a lot of recruiters try to sell: People think that just because they are part of the same wing that they will automatically have an "in" when it comes to being the latest hire. You will always hear stories of the dude that enlisted first and eventually got picked up, not so much of the ones that didn't; and trust me, there are plenty out there that were never picked up. Personally, I'd probably put being enlisted in a unit first on more of a 60/40 chance than calling it "highly successful." I've observed it both ways on round table discussions with the bros: (1) "Meh, this guy is a bag of ass and we want nothing to do with him" or (2) "This guy is on point and I want him in this squadron tomorrow!" Of course those are extremes but you get my point.
Bottom line: Enlisting in a unit first is a double edged sword and who you eventually become in that unit (along with meeting/exceeding all the other objective requirements) is what will eventually get you hired (or not).
My advice: Start getting your foot in the door now with off the street applications if this is something you really want. Getting snatched up on your first try will be great; but if that doesn't happen, every application / interview opportunity you have will be a chance to build up experience for whatever subsequent boards you decide to try. If you do decide to enlist or commission into a unit first, then your goal now turns into becoming the dude that the squadron wants on their team. Luck and timing, as brabus mentioned, will also play a big role with that.
Lastly, check out some of those professional consulting firms that help with application & interview prep. I've heard some good stories / testimonies over the last few years.