It’s a fine thing to be in love and then to marry and it’s just as good to marry and then to love.
It’s a good to plot out your novel, sketch your characters and then write all the words out one by one, starting from the beginning and finishing at the end. It’s just as good to write with the first word that comes into your head and continue until the last word is written and all the while making up characters and plot as you go along.
In truth though, although you can organise your life or write a novel in more than one way, some ways are easier than others. As to which is the best for you? Well, that is for you, and only you to decide.