This common phrase is believed to have originated from the literary fairy tale The Ugly Duckling, by Hans Christian Anderson.  From the looks of it, the term began being used in a figurative sense and unrelated to the story sometime later. An example of that is seen in the Stevens Point Daily Journal, 1883: "She gazed me at through her gold-rimmed glasses then remarked to Mrs. Maria, as though I were  not present: 'If this is the ugly duckling, 'pon my honor she does not strike me as so plain as she has  been painted." Read about it all  here . 

There are numerous ideas surrounding the origin of this phrase and no search could definitively give an answer. Click here to read about the varying thoughts. We use the phrase to describe needing to get all the details together before beginning a project, especially the smaller details.