When to start?

So, two parts to this thread. I'm hoping to 1) receive some advice on my next steps as an aspiring investment banking analyst and 2) facilitate and start a discussion for younger guys looking to get some tips on what to do. Yes, I know there are PLENTY of threads similar to this, however I think that it'd provide a platform to discuss based on specific situations; bringing me to my own:

For background, I'm a rising sophomore. I'm currently an investment banking summer analyst at a boutique investment bank in my town. It's a position that I actually landed along with two target school rising sophomores (Michigan and NYU students), and I'm a double finance/economics major at a non-target. While my school is rising in the IB department network, it still remains a non-target (on the verge of breaking into the semi-target range).

So, I'm personally curious as to when I should start networking for next summer. I have a list of 400+ contacts from hedge funds, FoF's, private equity firms, investment banks, and equity research firms. Although that seems incredibly broad, I think all experience is good experience. With that being said, considering I'm right next to NYC and in a hedge fund hotbed, I'm wondering as to when I should reach out w/ cold calls/emails for summer 2017 summer analyst positions. Any advice is good advice!