I didn't even get interviews for my placement (that I'm on now) until August, though I did start to apply incredibly late. I was working 12 hours plus my second year, so I left finishing up my CV and applying until mid May (post exams)... dolt!
FYI, I applied for two via the University (that were actually advertising for placement students) and speculatively wrote to 46 other companies... only 15 bothered to reply at all, and only one gave me a telephone interview. So don't be put off if you send out a ton of letters and emails and get bugger all back (even more so for emails, where they could at least take 5 seconds to hit reply and paste in a form letter).
My grump, TalkTalk, check which ISP you'll be on if you have to move out for your placement