The REC button is visible at all times at the bottom right portion of your screen. Anytime you hear an action call on set, you can instantly record the time (and date) of this moment, even if you’ve not yet created your first slate. When you stop recording, you will be presented with a dialogue to choose where you want to store the just recorded take. You can also assign the destination manually while the take is running: push the left red button in the Record bar that shows a slate board with a question mark inside.

The dialogue that pops up shows a list of slates on the left side, and a list of takes on the right. Assign which slate and which take to store the recording to. You can also choose a New Slate and/or New Take.