You can't make a specific ADR for the counter, but you can request it as a preference. If you are dining alone, and there is availability, they may even ask you to sit there. The counter does not have 15 seats, only about 8, if I recall correctly, so unless you go at 5:30 pm when they open or sometime after 9:30 pm prior to their close, the counter may be full. When you check-in, tell them you would like to sit at the counter; if it's ready, they'll seat you right away. If not, they will tell you how long the wait is, and if you're okay with that, you'll get it anyway. It couldn't hurt to call the Dining CMs and have them make a note, but it's no guarantee.
Same rules apply to CG and FF, in my personal experience. CG's counter gets too crowded as it neighbors the bar and the servers collecting the food. FF was very nice at the counter -- good interaction with the chefs -- but the heat coming from the kitchen may be exactly what you don't want on an 85° Floridian afternoon. Jiko was somewhere in between with regards to comfort. I enjoyed it and I would do it again, but on our next trip we'll try for a table.