Potty Training

I HATE potty training! Jacob turns 3 on Saturday and it's time, but he doesn't seem to realize that! He got new Thomas the Train big boy pants from Santa for Christmas and I was sure that would get him excited. Nope. He'll go sit on the toilet for all of about 30 seconds, proudly proclaim he's done and start to climb down. I tried today to make him stay there and tried to talk to him about what to do. I turned on water. We waited. And we waited. After about 5 minutes, he gets down and declares that he's done. I've done the whole timer thing where we go in there every 15 minutes but that doesn't work. I know all the lines of "He'll get it in his own time" but I don't like his time! I want it now, gosh darn it. Anyone have any amazing tips for potty training? You'd think that by kid #5 I'd have this down pat, but I don't. :(