It actually carries fairly little weight, whether or not somebody is a first-time offender. After all, everyone is a first-time offender the first time they are arrested; Bernie Madoff was a first time offender when he was arrested for stealing billions of dollars. The main factors involved are the seriousness of the offense and the intent (as seen by the court) of the defendant when he committed the crime. Furthermore, while judges often respect prosecutor, etc. requests, they are not obligated to follow them; and often, a defendant's cooperation is discounted is it appears he "came clean" only to save his own skin, not out of genuine contrition (e.g. did not come forward voluntarily, but only started cooperating when caught). If your son as received the appropriate number of years, basd on the sentencing guidelines, for the specific crime(s) of which he was convicted, and he also met the criteria to be convicted of that crime, then the sentence is probably not excessive--which does NOT mean that you and your son should not try to appeal it on any available grounds. He should speak with a criminal defense attorney, espcially one who specializes in appeals.