This is a paragraph from Sony article:
If you don’t have the luxury of an external timecode
generator, you can still help Vegas Pro software make your syncing task easier by synchronizing the time stamps on each camera before you shoot. If you’ve done this, add your media to the timeline, select each event that you want to synchronize, and choose Tools | Multicamera | Lay Out Tracks Using Media Date/Time Stamp . This method is a little less exact than using generated timecode because each camera’s time setting could be slightly off, but it’ll get you very close and you can manually make any minor adjustments that you need afterwards.
Cool… but when I import files from Canon 5D, the time stamp column in project media is empty and the option doesnt work.