It looks like the timeframe is one of the last selections in the wizard before you generate the report.
Does anyone know of a way to get resource data into a timephased report like this? How about custom text fields on the task? I'm specifically trying to create a report that gives me hours by resource by phase of the project, so I created a custom text field on each task (phase, like requirements, design, development, testing, etc). But I can't figure out any way to get that data into a single report.