i will use DATE_ADD,now if i want to get a rand time from 2012-10-1 to now,how should i do?

Code:
  created=DATE_ADD( DATE_ADD( DATE_ADD( DATE_ADD( DATE_ADD( DATE_ADD(
         NOW(), 
         INTERVAL 1 YEAR),
         INTERVAL 11*RAND() MONTH),
         INTERVAL 30*RAND() DAY),
         INTERVAL 23*RAND() HOUR),
         INTERVAL 59*RAND() MINUTE),
         INTERVAL 60*RAND() SECOND)
when i use the above code ,it get time isn't what i want. thank you.how to correct it?

eg: 30*RAND(3) what's the value will be?