Here, in the bottom two illustrations, you can see a comparison of a preliminary rough with the finished illustration of the Old Man from the Border who lived in the utmost disorder, who danced with his cat and made tea in his hat.
I usually begin with rough pencil drawings and notes to establish a conceptual response to the text. 
You will notice at the bottom of the drawings that there is an indication of the time taken to complete the illustration.
You may think that timing such work is a bit daft and obsessive, but it is important for me to know my pace in order to keep up with the publisher’s deadlines.