Free Trial for January Only

Trial offers are a good way to generate interest in your product. What I would suggest, however, is that you offer, say, the first 30 days free (as opposed to the month of January), after which, the user can choose which package to use - free, paid, or premium.

This can really help you convert people who are on the fence by letting them try it, risk free, for 30 days, and then start paying if they want to continue using it. As well, there may be people who won't pay to try something at all, even if it's a minimal amount, but for no risk, they'll try it, and then get hooked.

I think if you want to get people hooked on your service, you would do well to offer a longer free period, and also make it free depending on when they start using the service, no on a calendar month for everyone.

My logic is that the service in order to "hook" users needs to prove its worth and also become a part of everyday work for your customers. Is one month enough to accomplish that? What about for people who sign up three days before January ends?

You also need to see what other players in the field (and it's a crowded field) are doing, both the established companies (Monster, Dice, etc...) and the strong newcomers (ie, careers.stackoverflow.com). Borrow their good ideas, but more importantly, compete based on whatever free time periods they offer.

Having a free for the month of January has advantages and disadvantages.

The advantage is that it lets you test how well your PR works. If you try to publicize this during December then you should see a large number of people signing up right at the beginning of January, because of the deadline, and this will tell you how well you were able to reach people.

The downside of doing something just for one month like this is that it's a big dis-incentive for anyone who stumbles along your site after January 15. Those people will think that you need 30 days to evaluate the site (since you gave some people the whole month of January) and then will feel they won't have long enough to evaluate and therefore won't sign up.