Right now, the servers are at 696+M out of 1300M after 8.75 days, with 6.25 days to go on the quest. On straight progression, that is about 79.5M balloons a day. With about 600M to go, we would need 100M a day. However, the first days were likely slower as people were still starting to get the material from buffs as well as people getting a late start on the event. Additionally, the progressive rewards for donating balloons include 2 Petite and 2 Enormous cakes, which should also add to the total.