Summer Associate positions (S&T)

Hi everyone,
I see that people have been interviewing for summer analyst positions, but what is the time frame for summer associates? I applied at every bank online since my b-school isn't really a target and most banks come to recruit for middle/back office positions. I did my applications in December/early Jan, and so far I haven't heard anything except for one online "candidate screening" request that I completed. Is it still kind of early, or should I be worried? Also, if my ultimate career goal is trading, what are some other summer positions I should be considering?
For those of you who have interviewed candidates: do you know if anyone is ever actually selected from those online applications, or is it extremely rare?
On a slightly different topic, how important is GPA for these positions? My GPA is average but my GMAT is pretty high so I put it on my resume. I hope it helps but I don't know if I'll be asked about my GPA in an interview.
Any advice is appreciated. Thanks!