Definitely check with the front desk of your resort as to what time they run the room charges. When we were at AoA in 2013, they would run reports twice a day do check for guests who were close to their charging limits ($500 at AoA). If a guests was over about $450, they would put the charge through right away so that the guest wouldn't find themselves out at the parks with no ability to charge to their rooms. I don't know if every resort runs those reports twice a day, but I had 3 different front desk CMs at AoA tell me that's how AoA was handling it at that time.
I've had no luck getting a CM to front load gift cards on our room account for me. It isn't a big deal as I usually don't have a lot of gift cards to use anyway. I do wish they would change the room charging limits, though. We pay as much for a suite at AoA as we would for a standard room at a Deluxe yet we have a $500 limit at AoA but would have a $1500 limit at the Deluxe. On our last trip we had 6 people in our room (3 adults, 2 Disney Adults (teens), and an 8 year old) and no dining plan -- plus our son and his girlfriend were traveling with us (on their own reservation, though), and we paid for some of their snacks and a few meals. We were going through $500 every day or two. And I actually had a few hundred dollars in gift cards on that trip and it was a challenge to get to the front desk to use them before they pushed the room charges through to the credit card.