How to create a JOB to be executed at some specific time.

The easiest way would be to use SQL Server Agent to schedule your job to run every day at 12AM.

This link should point you in the right direction:

http://msdn.microsoft.com/en-us/library/ms187880.aspx

You need to make sure that the SQL Agent service is running on the machine. You can create a job in two ways, and the first leads to the second. Inside SMSS go into SQL Server Agent->Jobs->(right-click)->new jobs

from there you can give your job a name and create any steps from 'Steps' and set the time from 'Schedules'.

the second way to create a job is via script and if you create the job initially via SMSS you can script that job out to a file to see how it is created.