320 backlog is aprox 4 years now if you want it straight from manufacturer.
It's more or less correct (2015 for A320, 2018 for A320NEO) but sales and production talk constantly. If sales is pursuing a customer as big as AA, they make sure there are slots available to make a batch earlier than the "normal" availability date. If they don't get the sale, they try the next potential customer. If that doesn't work, there will always be someone willing to get their aircraft earlier than scheduled to pick up these empty slots.
With so many planes for AA, not sure there are many slots left however, even with Delta and Southwest looking at ordering "something." Perhaps one, but not both airlines, most likely...