I would recommend having at least 5-10 blog posts live before you really start to drive traffic. You want a decent amount of content available for your visitors to look through - this improves your time on site and lowers your bounce rate.
As for a posting schedule, there is no hard and fast rule. I know some bloggers who only post twice a month, but they are more active on social media or in email to keep their readers interested and engaging. Others post every day of the week to constantly have new posts to share on social media.