First off, an email... she probably won't get until Monday. It is a holiday weekend, so she could have gone off to see her family. Second... I agree with most everyone, you should wait. The thing is... I know the weekend is here, and if you wait until Monday, you won't have lunch until later... and if she works she probably likes to schedule ahead of time. I don't know if anyone has read the book just not that into you: but many of us females have... and it suggests after about 3 days.. if you haven't heard from him.. he's just not that into you... If you are interested, don't give up, call her Sunday evening around 7, and mention lunch again for two days later... have a suggestion of time and date ready, so she knows you are planning it and thinking about it.