Questions Based On The First Panel Of One Of This Week's Comics Part I

From the first panel of this week's Return Of Bruce Wayne #5:

Now, maybe this is just me, or maybe it's the really odd way time gets portrayed in comic books...but Tim Drake was Batman's partner for a longer period of time than Dick Grayson??

I always got the impression that Dick Grayson started as Robin at a younger age than Tim did (check for example, the portrayal of Grayson's age in All-Star Goddmaned Batman...not canon, I know, but still)...and Dick while was Batman's partner until he left for college, whereas Tim, if I recall correctly, dropped out of high school to become Red Robin and search for Bruce. So, as I perceived it, Dick started younger and stayed at least a little bit longer.

Hey, I could be wrong. Maybe I'm just old and the cognitive dissonance of the possibility of anybody being Robin longer than Dick Grayson is warping my brain. Or maybe Superboy-Prime just punched the universe again...I'm just askin', you know?