Daniel Zaleski Weekly, Wednesday 9AM seems like a good solution for all social media ;)
Jana Babackova For us for sure, all data are based on our own usage statistics, but we have quite specific target audience. Monday is good for our authors historically, since they usually prepare their articles during the weekend, however published on Wednesday get the most attention. For professional use, Monday (morning) is bad because of information overload + tons of e-mails you have to process before you open feed(s) for last three days (Friday included). One can overlook interesting post quite easily. But if we want to be more focused on Twitter, Monday afternoon is a good start. We can try that.
If you open any social media related infographics, you can read more or less the same. Facebook for private use is read by users on Th, Fr + weekend, but different for companies, there Mo (after lunch) + We works. Twitter peak is on Wednesday, LinkedIn Tu We Th, Pinterest has weekends, Instagram Mo Th, Google + Wednesday again. To be effective and promote company posts during the week, you can pick e.g.: Tu LinkedIn, We Facebook and Google +, Th Instagram, Sa + Su Pinterest...
Daniel Zaleski Thank you for sharing your knowledge!
Jana Babackova ... more serious, less fun today ;) Dates & times are based on our analytics data, do not take it like universal truth ;)