The MathJax developer's drop-in hour is at 16:00 UTC (noon Eastern, 5PM UK time) on June 25th. You can join via the following link:
https://app.sococo.com/meet/AccessiblemathematicsThelobby-2-3XykZX1Z1Z67502117
Note that you must use the Chrome browser (and actual Chrome, not another chromium-based browser) in order to use the Sococo site (sorry about that). If you have trouble using the link, post a reply here, and we'll help you to get in.
See you there!
Davide