For better or worse, that sounds pretty typical, and not just for JD. I just took delivery on a 4110 that took about 50 days. If the unit would have had to come from the assembly line rather than through the dealer transfer program, it would have taken another 30-45 days, or so.
If a tractor model is not in inventory at the dealer where your purchase is made, the JD system offers a dealer two options. First, and fastest, is to find a machine on the dealer-to-dealer transfer program. This is where a spec'ed machine is found at another dealer and the dealer with the inventory agrees to give it up. The second option is to order one off the line.
Regardless, the JD system requires a dealer to piece together your order with all of the new parts arriving at a reasonable interval to the arrival of the tractor. Getting loaders, bucket level indicators, block heaters, mowers, attachments, and other options to the shop is part of the first step. Of course, it takes quite a few hours to put one together as ordered once the parts get to the shop. This is considerably different than our experiences with new cars because tractors are rarely "loaded up" with options on the lot, there are no real "trim lines" to choose from, and the production of tractors occurs on a more demand-responsive schedule compared to the auto industry, which produces vehicles on a demand-anticipation schedule.
Bottom line: your wait seems about right, and even blue tractors that are ordered versus purchased off the lot will take awhile. I'm sure you won't be disappointed. Especially since it sounds like you did your research to find the right tractor for your needs.