Where to focus networking depending on age

So i'm a rising soph at a top target. Going to spend a week and a half in san francisco for the summer, I want to use the opportunity to network, as I would love to work in MBB in the San Francisco office. Question is, since it's essentially impossible to secure a MBB summer internship in the summer between your soph-junior year, should I focus my networking on companies where this IS possible, such as Deloitte or Accenture or Oliver Wyman, to secure an internship for the summer? Or should I start my MBB networking now (considering the fact that two years might be a long time for them to remember me).

Thanks for any and all input.