You've already setup an account, so now it's simple. Your reservation numbers are relevant only if (a) your are booking 180+10 (i.e. you want to book all of your ADR's for your entire trip at the 180 day mark or (b) if you are using a dining plan and don't want to pay for the prepaid ADR's (CRT, dinner shows). Otherwise they don't matter at all. Anybody can setup ADR's even if they don't have any trip/reservation planned.
At your 180 day mark, just make the reservations online one at a time. Depending on the ADR, you might need to put in a credit card as a guarantee that you'll show up. You'll get an email confirmation with number for each ADR. You'll want to save these confirmation numbers as the Disney website is notorious for "losing" your reservations and will ask for a number so it can "find" them again for you.