Welcome aboard, snotty! Back at the turn of the millenium, when officers of all elements wore gold rank insignia, the dress instructions specified that nylon braid was worn on DEU tunics. Naval officers had an additional section specifying gold lace for their ranks. In practice, you got what Supply gave you and nobody batted an eye. I do think the braid with gold content looks a little nicer, but it can also crease permanently, so your mileage may vary.
Hold on to all your issued kit and wait for instructions. If they want you to get your DEUs tailored beforehand, they'll let you know. Otherwise they may want you to use a certain base tailor, avoid unnecessary pay-and-claim paperwork, etc. You'll eventually be made whole if you do take care of it yourself (initial tailoring is at public expense), but it's good to avoid creating extra work for others.