I find it really interesting how Taylor, Carrie U and Miranda Lambert are all currently on or about to start their fourth album cycles.
For Miranda, her lead single took several months to climb the charts. It peaked at #3 on Billboard Country Songs, although I attribute this more to the fact that it was just a bad song than anything else...
It will be interesting to see how Carrie's "Good Girl" does since it is a bit of a different sound for her. I think she'll easily be able to take it to the top 5 on Billboard Country, and reaching #1 shouldn't be a problem.
The success of Taylor's lead single will depend on the song choice, the promotion it recieves, what else is out on the radio and whether or not it leaks early. Hopefully it's something a little less pop influenced. I also wouldn't mind her releasing a slow song as a lead single, although I highly doubt that will happen.