If you’re about to put your first podcast on iTunes, don’t. Wait until you have at least 3 episodes recorded (5 is better) and THEN put them in iTunes.
This way when people listen to one of your podcasts, they can go back and listen or download more of them. This will give you a better shot at ranking in iTunes and getting more listeners and subscribers.
Next, release 4-5 episodes every week for two months.
Get your list members and friends to subscribe, listen, rate and review.
This will almost certainly get you into the “New and Noteworthy” section of iTunes, gaining you new listeners and subscribers for as long as you remain there.