Dan Zarrella tells us when and how often to tweet.

While late afternoons are great for a variety of things, particularly creeping out of work early, it seems to be the case that you should probably be tweeting. A lot. Somewhere in the ballpark of 22 times per day, according to Dan Zarrella, who knows a thing or two about social media optimization but refrains from referring to himself as a “guru,” which appears to be a smart move.

Dan Zarrella, according to his website, is a social media scientist. He has 33,000 followers on Twitter and works for HubSpot, where he sifts through millions of tweets hoping to uncover market trends. He’s also keen on rap music, as mentioned in a blog post about social media and the hip hop game.

In a recent webinar entitled “The Science of Timing,” Zarrella shared the results of nearly three years in data mining. While fine-tuning a social media strategy can vary based on goals, when it comes to timing Zarrella believes the best way to reach people is to communicate while the buzz is low. This “down” time seems to strike during afternoons while news sites and blogs are slower as well as during the weekend. According to Zarrella’s analysis, retweet activity is highest late in the work day, between 2 and 5 p.m. He even created a tool called TweetWhen which provides customized graphs showing which times and days land the most retweets-per-tweet.

Twitter clickthroughs and comment activity leap during weekday mornings, a time when news sites tend to find a significant decrease in pageviews. As weekends allow users to devote more time to patrolling content and many places of business frown upon social media shenanigans during company time (the nerve), activity increases here as well.

For more info, see slides from the webinar and check out Nieman Lab.