I think if you have little traffic and your site is not established you'll probably get rejected by their review team.

If you need traffic for your website then you can use social network and follow people of different niches because directory services can includes different categories so you can find traffic for it or do free classified Geo based posting.

You can put text link ads up even if your traffic is low as long as you are adding value to the advertiser. Are you looking at the networks or to sell ads yourself?

How much traffic are you getting? Did you apply to TLA?

I can't think of any reason not to monetize a site right off the bat.

As long as your advertisements are presented in a non-invasive way, no one should have a problem with your site utilizing monetary marketing ideas.

Unless your site is a personal diary or project of yours, what is the point of running a site that has no potential to make anything?

Monetize it.

If you are referring to subscribing to places like adsense in regards to your traffic, I'd tell you to read their terms of service individually but I don't think you'll have a problem even with little traffic. I know blogger allows people to host adsense even on sites that are less than a day old and will probably never get developed past the first week.