yes it is
Once upon a time...
Once upon a time ..............................
Once upon a time there were subcontinents...
Once upon a time there was a pretty pony AMICABLE.
once upon a time a beautiful princess lived in a castle
Literary/literacy sentence or story openers that involve time. Eg. Once upon a time...
Once upon a time, One Morning and more...
It usually begins with "Once upon a time,".
Once upon a time a beautiful princess lived in a giant castle with her family. OR I sat upon the rock watching the horizon.
Once I understood your question, the answer came easily. Once upon a time there was a simple question innocuously posited.
When you wish upon a star, it makes no difference who you are. Once upon a time, I read a bedtime story to my little nephew. The frog is poised upon a lilypad.
the usual opening line of fairy tales is the "once upon a time"