I'm 7.5 years out and according to my clinic, I'm still supposed to wait at least 30 minutes after eating to drink (and I do...). I'd say for most clinics, that rule is for life.
I don't dump, but dumping occurs once your food goes into your small intestine - so yes, that would probably take about 30 minutes, give or take... Some people call any kind of vomiting after eating something "dumping", but that's not true dumping. Dumping is when your small intestine goes into overdrive trying to deal with the all the sugar or fat you managed to consume in one sitting. Sweating or chills, dizziness, heart palpitations, cramps, and diarrhea are all common reactions. Nausea can be as well, but not as common.