I know both are closely related, but I have trouble deciding which to do first / spend more time on. It’s like the chicken and the egg. Which one will lead to an increase in the other? Or must they be done simultaneously?
Create the content and, if the content is good and it's uploaded to the right places, the audience will come. You'd be amazed at how good content can spread virally. I had a piece about predictive analytics in the gaming industry that I uploaded on Academia.edu and it got picked up by a blog that increased its audience exponentially. My article was about casino gaming analytics and this blog was about gaming gaming, i.e., video games, social gaming and eSports, and yet it pushed my article up the Google rankings for "predictive analytics gaming" to where I am still on page one for that term, which is great because I run an analytics company! It's not quite the chicken and the egg, more like the the egg and the eagle; one has to be created, but the other can soar far and wide and can be seen by an audience that the egg can only dream about. (FYI, .edu websites are powerful for social media marketing because Google considers them more valuable and ranks them higher than normal .com websites.)
100 % Creating Content. Because The Audiences Automatically Are Attracted when you have a Great Content .
What type of content? Tweets? Blog posts?
I'd start off by building 4 weeks of blog posts, tweets, and any other social profile updates. Once this content is scheduled focus on building the audience. Then when your treasure chest of content and social profile updates starts to run dry simply create more fuel for the fire.
make a good content and take a brake with creating audience
Create content because if you have good content you will get great audience but if you get audience and have no content its useless.