There's no magic number. So...no perfect answer to your question.
It also depends on the quality of your article.....how attractive it is to "readers"......how "attractive" your sig box is in inviting "them" to click on your link(s)....how well the article targets the type of traffic you want.....if the article is interesting enough to be picked up by ezines and websites for content (called viral marketing)....how targeted "their" audience is in relation to your intended audience...and a whole lot more.
That said...you should try to write and submit 2-4 quality articles every month .... every week if you can handle it. Consistency over time is the real magic.
