^^ The year is almost over and we have Christmas, and Hanukkah from the 20th to the 28th, which wouldn't be the best time to gain support from the troops or the public for a ground invasion.
The US built up a large number of ground forces along the Iraq border over a month or so before that invasion, so if something similar was going down soon I assume there would already be noticeable operations going on. Also, before a ground invasion there would first be a major amount of attacks from the air.