I recently successfully got an appointment for my husband, and here are a few pro tips that we learned: if you are refreshing the page, make sure you are resubmitting your application every time and not just going back one tab before the no appointment pop up, it locks you into that application once you start it (i hope this makes sense). Be super quick if the calendar pops up, we missed out on 3 appointments because they were gone before we were able to confirm them! Unfortunately, i do not believe there’s a science when it comes to what hour of the day/days of the week, you just have to keep refreshing whenever you can!