Would it be awkward to say "I once wanted to [do something]" instead of "I used to want to [do something]?" Or are they interchangeable?

Native speaker’s answer
Rebecca
You can say "I once wanted to do something" instead of "I used to want to do something". They are mostly interchangeable. When talking about a habit or something you did more than once, I would use "I used to". Ex: I used to want a puppy. Now I want a cat. => I once wanted a puppy. Now I want a cat. Ex: I used to wait at the door every day until my mom came home. Ex: I once waited at the door all day until my mom came home.