Blurb in the Navy Enquirer sez there will be a certain-period-of-time changover for the new uniforms and the clock will start ticking when the NEX gets them in. Don't know how long that time will be, but usually when they do new uniforms, it's been about 12-18 months. "When" is sometime mid-08, probably SD and Nawfolk will be the first to get them.
If you're buying My First Ensign uniforms now, you'll probably never need wash khakis; they'll be Officially Gone by the time you hit the Fleet and need them. Likewise, you won't need the Smurf Cammies (Smurfies?) until then, so go spend your phat Ensign paycheck on a big TV or a Harley instead.
Show up for API with at LEAST two sets of CNT khakis. You'll get your bags at some point (depending on the supply chain) and then you'll just wear khakis for duty, or G-d forbid, a PRB and going to see the Skipper. You'll probably know at least a few weeks in advance before you need blues/chokers/mess dress, enough time to go get them.
And for the love of G-d, get khakis that FIT. You see all these Ensigns walking around who are rapidly returning to their pre-OCS waistlines and starting to resemble sausage casings. You're not fooling anybody. If you lost a lot of weight at OCS, you're going to put at least some of it back on, especially if you're in A-Pool for a few months. You're not Moses, quit living in denial.