For Samson the booty scooting started when he was a pup. This told us 2 things, he needed his anal glands expressed regularly (for him it's every 2 months) and he has a tail pocket that needs to be cleaned regularly. You can wait but that's up to you, if you can move up the appointment I would because obviously it's bothering him. The other way to tell when it's time for an expression is sometimes you can smell the glands, it's a really gross smell. It doesn't smell like feces, it's a different smell but still gross, nothing I can compare it to. I just track our visits so I can take him before it gets to the smelly booty scooting point LOL Same with the tail pocket I make sure to do it regularly so it's doesn't get to the point where it's bothering him.