When do you start trying to take dragon?

Obviously the time to take first dragon varies a lot because of a wide variety of circumstances, like how well you bot lane has pushed, how far behind the jungler might be, or the presence of a Malz / Heimer / Shaco who are super effective against dragons. But, on average, how far into the game do you start trying to take dragon?

I ask because I tend to be very focused on dragon early game, when my team doesn't seem to care about it. This is especially true with Infernal and Mountain drakes, and less true with the Cloud drakes, but a notable team-wide buff seems like something that we should get as early as possible, yeah? I mean, as i understand it, the whole reason for the 1/1/2 lane arrangement was for the extra pressure around dragon, back when it gave the coveted gold bonus. But now, no one seems interested in taking the dragon until the laning phase is almost over, which kind of makes that argument invalid. If we're not doing dragon until people are roaming into one-another's lane, why stick to a meta that's based around needing extra laners near dragon?