Related Clues:

• ___ in a blue moon
• First word in a fairy tale
• On a single occasion
• '___ bitten, twice shy'
• 'Going ___, going...'
• In olden times
• ___ and for all
• At some prior point
• Way back when
• Story opening
• Previously
• Many years ago
• Fairy tale start
• In the old days
• Infrequently