How many unique articles and content is good to start out with on your website before you start marketing it?
Before we start with marketing thing, we need to launch our website in full-ledge. There should be not under construction or irrelevant content. And one thing that you should keep in mind "be original, make quality, do market". It it depends on you that how many of the article you may make (there is no number i can suggest but i can tell more content).
That's not the quantity matter but the quality. If you have only one page content but it is very helpful or information such as professional essay, then it is good enough for you to start the marketing
from my experiences you need at least 10 article for your website 5 article to directory site 1-2 article for press release site In less than 48 hours. I have my domain got in 1st rank in Google with less than 1500 intitle google competition on my keywords.
Like has been mentioned above, it's way more important to focus on quality content as opposed to quantity. Just make sure to update it constantly, and go ahead and market it while it's growing so it looks natural to both search engines and your visitors. The amount of content you'll ideally want to go for depends somewhat on what exactly you're trying to promote/achieve from the site.
I have to agree with earlier posters, focus on High Quality content and make sure your internal linking is user friendly, Google loves good internal linking.