First draft of a first book

It occurred to me the other day that writing the first draft of a first book can be compared to many things - but I like to compare it to a stumble across a darkened room.
But not just any room.
I like to check on my kids just before I go to bed and, as I was trying to sneak quietly out of my daughter's room the other night, decided that this trip was not unlike writing the first draft of the first book in a new series.
Let me explain.
You know the starting point (the bedside). You can see where you have got to get to (the lit hallway outside). But the route you take to get there can end up very different, even if you have envisaged it clearly in your mind beforehand.
There's a night light in the room, which changes colour four times in a cycle, from quite a bright blue light to a dim red glow. At any moment, your path forward can be plunged into darkness, or revealed in a burst of dazzling light.
There are any number of pitfalls waiting for your uncertain step. Obstacles that must be avoided, or stepped over, or even moved to one side to enable you to go forwards. Some feel soft, and safe - but could make a terrible noise. Others are sharp and will cause you lingering discomfort.
Sometimes the best route is to take a few steps sideways, even one step back - but always you must press on forwards. Head for the light.
But don't rush. Often, when you are striding forwards confidently, a sudden plunge into darkness can throw you off balance. An obstacle you were sure you could avoid is suddenly somewhere underfoot. A wrong step could be disastrous at this point.
Occasionally you must pause, wait for a little extra illumination to be thrown on the subject, to see your way forward.
Naturally reaching the end is a relief.
But take time to look back and see where you mis-stepped, or over-stepped, or perhaps could have strode out a little stronger. There is always a better route to take. Hindsight allows you to examine your progress critically, see where you might do better next time.
But never forget, you have safely reached your goal.
Anything is possible from here.