Unless you are dealing directly with the stock carver themselves, it is almost impossible for a retailer to know when and what they are going to get from said carver. All they can go by is past delivery history, and that is probably what they were projecting their estimates on.
This is a cottage industry where production capacity is almost non-existent when compared to other industries. Having known stock carvers in the past, and how they work, the delay could be a result of literally anything, i.e. being sick, not liking to run a particular stock pattern, taking an unannounced month off to hunt, broken machinery...etc. Or it could be as simple as not having high grade wood on hand, which even the carver might not know when he can get again.
If you are in a real hurry, I would look for other wood grade options if they are available, because to put it bluntly, two months is nothing but a blink of the eye for how long I have seen it to take to get a good pre-carve.
Good luck.