progressive disclosure – Recommended Font Awesome icons for progress

I have a flashcards-type application, and I want to place a simple symbol on each set of cards, to indicate 3 possible states:

  • not started
  • started but not completed
  • completed

For completed, I already have the check mark in a green circle. I am looking for recommendations on 2 other icons to represent the first 2 states (not started, started / in progress).

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