What is the first step to display waveforms from source audio in a timeline?

Loading the master clip into the source monitor is the correct first step for displaying waveforms from source audio in a timeline because the source monitor is specifically designed to provide a visual representation of audio and video content before it is placed on the timeline.

When the master clip is loaded into the source monitor, you can visualize the audio waveforms, which allows for precise editing and alignment with video or other audio tracks. This step sets the stage for subsequent actions, such as toggling controls in the timeline or adjusting settings, but it is essential to first load the material you want to analyze visually.

The options that involve toggling or enabling settings assume that the source audio is already being accessed. However, without initially loading the master clip into the source monitor, those functions cannot be performed effectively because there would be no audio waveform to modify or view.