Hello, Colin!
You may absolutely book your Advanced Dining Reservations at this time, without liking them to your hotel reservation. If this were still well in advance of your check-in, your room confirmation # would enable to book those reservations early. At this point, however, you're good to go!
Because Disney Dining Plans are very popular, Table-Service reservations book up rather quickly at some locations. As such, I recommend that you either call Disney Dining directly, or go online
and make advance online dining reservations as soon as possible. Once at the restaurants, your server will ask if you are on the Dining Plan; you can show him or her your Key to the World card, which will list which Dining Plan you're on, so that your server can best advise you of what's included at that venue. Your Table-Service entitlements will be removed from the total linked to your Key to the World card. It's that simple!
Should you use the online advance dining reservation system, you'll also get email reminders about your reservation, including location, confirmation number, party size, date and time. We found this very helpful while at the park, since I could check each reservation using my smart phone, without having to write anything down.
Please send me any additional questions you may have about your dining options or anything else regarding your upcoming trip! I'd love to help!