Related Clues:

• ___ in a blue moon
• First word in a fairy tale
• On a single occasion
• Heretofore
• '___ bitten, twice shy'
• Have ___ at
• 'Going ___, going...'
• In olden times
• 'It's ___!' (thumbs-up reply)
• ___ and for all
• At some prior point
• Earlier
• Since
• Way back when
• Story opening