As a rule of thumb it's better for you to continue investing yourself as far as you can. The reasons are:

1. The later you raise money, the more your business should be worth
2. You are able to retain more control of the business
3. Fundraising is very time consuming and will divert your attention from making your business work

Having said that, if you're getting to the point where you can't continue to move the business forward (or at a good pace) without money then it's worth looking to fundraise.

Dan