That's a good question. I assume that IPO (Itinerary Planning Office) will contact you directly even though you booked through a
travel agency. Perhaps others will share their experience and correct me if I am wrong.
Now that I am thinking about it, if you have to place your room requests via the TA, do you have to make contact to IPO through them, too? What about if you book through a third party like Orbitz or Travelocity?
Here is my experience- I booked a CL reservation in January for a trip in October (with Disney). I did not contact CL and they sent me an email a couple of weeks before my 180 day reservation date, with a contact form for me to fill out and to indicate if I wanted them to make reservations for me.
As it turned out, I was away during my ADR day, they made all of the reservations I wanted and had notified my by 7:20 that morning.
I believe there are 8 or 9 BC CL GV rooms, all with full balconies in that category. Not sure where all of them are located, but many overlook the back entrance (lakeside) courtyard. These rooms would be fairly close to the lounge.