You can either sign up early and change your schedule later if you need to, or just wait. You can cancel your volunteer schedule anytime before 8 August with no penalty. If you sign up early, you’ll have more jobs to choose from and may not need to change any of them later. If you sign up after you know your meeting schedule, you’ll have to be more diligent about checking the website to see if there are jobs that will work for you. Student Volunteer jobs usually fill up quickly, but volunteers do change their schedules often, especially after the abstract acceptance notices go out (showing the date/time of presentations, mid-July this year). Even if there are no jobs available to fit your schedule at any one time, since other volunteers may also change their schedules, jobs will open up from time to time (but you have to check back often).