Well, all that you need to do is to enter the time and date in which you need to arrive, and then Waze will get down to it, giving you the best recommended time in which you should leave. Apart from that, you will also be on the receiving end of a reminder when the event is closer in time, providing you with an updated departure time as well which will be based upon real-time road conditions.
In other words, just set it and forget it. Planned Drives also make it far easier for you to keep track of your time and schedule. Using it is a snap – boot up Waze, enter a destination (Menu>Enter address in search bar). From the Waze ETA panel, click the Waze Planned Drives icon that is on the bottom left. The Waze Planned Drives screen will open up and show off peak traffic hours along your future route, where it will use its smart algorithms, aggregated traffic history and predictive analysis to figure things out.
If Waze has access to your Calendar and/or Facebook, appointments and Facebook Events will end up as a Planned Drives automatically. Expect Planned Drives to arrive on Android in due time as well. [Press Release]