You should have like 100 if you want a natrual traffic of 10-20 visitors per day. Just make one post per day. I promise you'll have 365 very soon.
I set up a new blog 1 month ago and i post it twice a day, most of my traffic came from blooger(on which i have hosted) and rest comes from google search for many keywords and in a month i am having more than 200 visitiors a day. So here the key is your niche and regularity of postings.