Both the older Snipping tool, and the newer Snip and Sketch have a time delay option.

In legacy snipping tool

1. click the dropdown button next to delay to choose time delay
2. click the delay button.  The app will disappear for the set time then trigger the select box workflow to highlight area you want to take picture of.
3. You can use pens and highlighters in app to bring attention to items if necessary, or to block off private information.

In newer Snip and Sketch

1. Click the arrow next to 'New'
2. Choose 3 or 10 seconds
3. it will immediately trigger the delay.
4. other steps are same as above for choosing area and adding notes.

esc key cancels a snip in progress