I signed up to judge maybe a month or two ago for both a local event, and some of the at-home events. As a disclaimer I have been judging for several years.
Regarding the local event, I got officially assigned about two weeks ago and got a follow up email a little over a week ago with slightly more info (this is the Greater SF/ Bay Area event). The JA said that interviews for the local awards will be in mid-March to early April and that she will be sending out a Doodle survey to figure out availability later on. She mentions that she is not able to see what other challenges specific teams are competing for, and asks us to try and be as flexible as possible when filling out the survey to help her coordinate times between teams and judges. She does ask for some help recruiting more judges, so my guess is that they are still a bit short.
Separately, I got an email from HQ almost two weeks ago letting me know that I was signed up for multiple events and if that was not what I had intended, to let them know ASAP. I have not been officially assigned, and the email said final confirmation of assignments will come in late February or early March. In a follow up email to this I was told that they expect judging to occur Mid-March through Mid-April and the JAs will work with your schedule to schedule interviews when you are available. They expect most to happen in the evenings and on weekends and buffered in about a month for the judging to occur so JAs can be flexible with the judges. They expect the time each judge to spend to be ~ 5 hours in total but may be less.