Automator Screen Capture terminal Help

I am trying to create an automator apple script for terminal that will let me run this script,
"
tell application "Terminal"

activate

do script with command "screencapture -W ~/Desktop/Review/pic.png"

end tell
"
The issue I am having is that it keeps replacing the same screenshot with a new screenshot rather than creating pic1, pic2 etc. I would love to be able to make use of that script and be able to take multiple screenshots in that folder. Any help would be greatly appreciated.