It's also pretty interesting to think about how Tim Drake fits into all this, at least in the Pre-Flashpoint continuity. Bruce started training Tim when he was 13, and Dick was at least 21 at the time. Which means that Dick would be like 8 years older than Tim.
Thing is, Tim saw the Flying Graysons' fall to their deaths. That's how he was eventually able to figure out Bruce was Batman. So then Dick couldn't have become Robin when he was 8. Tim would've been a baby back then, heck, he might not have even been born yet. Now, Tim's age when Dick lost his parents was never stated as far as I know. I saw in some website that he was supposed to be 3 at the time (but who knows where they got that from). That would mean Dick would be at least 11 at the time. Personally, based on the way Tim looked in A Lonely Place of Dying, he seemed to be 4, maybe 5 or 6.