You can start looking and preparing now. You just don't apply to the firms yet.
Since you are starting law school, you should now have a nice updated resume from the application cycle. Update it again. You now need to include your law school under education. You also might need to modify it to now target a potential employer instead of a potential school.
You can check the NALP Directory
to find out the names of some firms that hire from your school and also hire 1Ls. Do a bit of research and see if there are any firms you absolutely dislike or any in which you are especially interested.
When school starts, you can chat up some of the 2Ls and 3Ls and find out where they did their 1L summers, if they went through Career Services to get the job, or if they did their own mass mailing campaign.
December 1st may be the first day you can send out applications for jobs, but there is still work you can do now to make sure that you have your resume and cover letters ready and that you know where to send them.