Build Your Mailing List Or Die!
Know this: your marketing efforts will not be worth much if no one knows who you are. It doesn't matter how amazing your blog is, or how brilliant your podcast is, without an audience, none of it matters. Which is why it's so critical that you build a mailing list now before all of the newbies realize just how valuable email subscribers really are.
Unfortunately for those of us who know better, human beings have a limited attention span - and once they're distracted by something else - say Facebook or Twitter - then it becomes next to impossible to reel them back in. So if you wait too long, you'll lose your audience and then marketing will become much more difficult for you.
My friend Paul Colligan of Top Dog Marketing once told me that it takes him about 100 days to establish a new relationship (aka get a prospect to subscribe to his mailing list). And while I'm sure he's exaggerating a bit, the fact remains that it takes time to build a relationship - especially online. That's why I recommend anyone with an online business start with at least 1,000 subscribers in their subscriber database. Anything less and you're just putting too much pressure on every single piece of content you create.
This isn't to say that you need to go for the most subscribers possible, either. You just need to realize that the more subscribers you have, the less stress it's going to put on you when creating your content. I know from experience (as well as when I talk to other marketers) that many who start out with a small list at first end up getting overwhelmed by it and give up after about 200 subscribers - that's just way too many people you're trying to market to at once.
Conclusion