Your attorney is mostly right. But we've had a number of clients apply at land-crossings, such as Peace Bridge, and explain that they're just applying now to m

Your attorney is mostly right. But we've had a number of clients apply at land-crossings, such as Peace Bridge, and explain that they're just applying now to make sure that they can get a TN before actually moving to the U.S. and the CBP officers consistently have been fine with this. You still would need to enter the U.S., however. I would recommend calling Peace Bridge and asking. You should be able to get an answer.