The announcement says, "The one-time $25 credit will be applied to their Self-Serve account within 72 hours of activation," so I wouldn't get too worried quite yet because it hasn't been 72 hours since Saturday.
That being said, I had a referral done on Sunday evening, and I was pleasantly surprised to find the $25 credit in my account on Monday morning. But that was just my experience, and it was given to me earlier than necessary. I would give it 72 hours before you should start being concerned that something might've gone wrong.
