I received an e-mail from a principal earlier this week that was sent to multiple candidates with a link inviting me to sign up for an interview on a website. Basically there were multiple time slots and if it didn't have a name next to it, it was an open slot and you'd write your name next to it to sign up. I just received a call from another district that invited me to come for an interview the same day, where I wouldn't be able to make it to both interviews. I just checked for the first school's online interview website and they had multiple time slots that were much earlier, so that if I changed the time I could make it to both interviews. Would it be acceptable to change the time? Also should I follow up via e-mail with the first principal explaining that I selected a different time slot? If so, what should I say in the e-mail? I don't want to seem flaky for changing the time, but it doesn't seem like it would be an issue since they have multiple other time slots available.