I underwent surgery three weeks ago, to remove a hernia from my abdomen caused by a hernia. I want to know if its safe to go scuba diving. Or if its too soon.

According to DAN (Diver’s Alert Network) :
"a sliding hiatal hernia does not by itself contraindicate diving." however a "paraesophageal hiatal hernia is considered a contraindication to diving."
No idea which you have but here’s the link for you to discuss with your Doctor.