whats the timezone shown in the pop out? Is it mine or can the user configure the timezone to be specified?

what if i have multiple google accounts and i want to show the aggregate availability. for example i have four sales reps and they all have free time between 10 am and 11 am. if all four are booked the end user should see the time slot as full, else till all four are booked the user should be able to book that time slot. if that possible?