just like to add something to this regarding the unique mount.
you need to either add 2x 1month subscriptions in which case you will get your mount in 3months time "30days trial + 2months" or you purchase 3months subscription and wait till the 30day trial expires to get your mount.

This is currently why most people are missing out on the mount because of blizzards strange wording.

The above has been confirmed by 2 in-game GM's