I just accepted a job offer and am planning to leave the company where I've been for almost a year. Today is Tuesday, July 11th and my new job is scheduled to start Monday, July 31st. Unfortunately, my boss is out of the office today and I would prefer to tell her that I'm leaving in person rather through Office Communicator, which is how we usually communicate when she is working from home. It seems to me a bit disrespectful to not deliver the news in a face-to-face meeting. At the same time, I want to give as much notice as possible so as to avoid leaving her in a precarious position. It seems like a lose-lose situation and I'm not sure what to do. What factors should I consider in order to determine the best way to go about resigning without burning any bridges?
Edit: My contract is "at will" and I really have no idea what my expected notice time is. I do work in a very small department and my boss mentioned she spent a long time trying to fill my position so I don't think it will be easy for her to replace me. She will be back tomorrow, as far as I know.