In mid-January 2005, Google pushed out the nofollow attribute to give webmasters a way to tell Google that this link does now count. Shortly after, SEOs and webmasters started to go on a "dofollow" campaign.
Literally, I see mentions of the term "dofollow" being used within a month after Google announced the nofollow attribute. The first time we used it in an article here was in 2006 and it was used in comments here as early as 2005.
But who was the first to coin the phrase? I am honestly not sure. That is the question a reddit thread and no one seems to know the answer.
I see WordPress plugins coming out as early as a February 2005 named dofollow. This Wiki page shows the use of dofollow on February 9, 2005 by Sebastian Helm. But was he the first? I doubt it.
Do you know who the first was?
Forum discussion at reddit.