In this and the following pages I take you through the different stages from day 1 to hatching at day 21.
We'll go step-by-step, slowly, carefully and with as much practical detail as you can take.
This series is expanded in my hatching club course, where I lead you by the hand in even more detail through the process and invite you to join my Hatching Club Facebook page.
If this is your first time incubating chicken eggs...
...and if - as I'm sure you do - you take it seriously, you can expect to feel two things: uncertain, and anxious. I certainly felt like that. It's only natural.
You've read all the books, you've seen all the questions on the forums. So much can go wrong at any stage ...
But if you can, try to relax and enjoy the whole process.
A mother hen goes through this without too much fuss. We'll use her as our role model as we take a leaf out of her book.
Of course, things can go wrong. But if you've chosen and stored your fertile eggs wisely, if you're careful and you don't panic, all will be well.
The candling pictures I use here and on the next pages are my own and
follow one of my chicks right through from placing the egg in the
incubator to hatching. This is what she looked like just a few hours
after she'd hatched.
See the white tip on the end of her beak? That's the 'egg tooth' which chicks use to peck their way out of the egg. she'll lose it within a day or two.
The answer is - quite a lot. It may not seem like it, and you won't be able to see much of it at least initially, but ever since the egg was laid it has been developing.
It will have stalled once the hen was no longer warming it, but make no mistake - if you have a fertile egg, development has already started before the egg goes into the incubator. Incubation kick-starts the process again.
By the end of this first week, your chick is one third of the way to full development.
The shell of the egg doesn't change at all on the outside until the chick is ready to hatch much later in the process, when she will start to peck through or "pip".
Until then, if you want to see anything you'll need to invest in a candler - either home made or shop bought. Both are good as long as the light is very bright, and focused.
There's really not much to see at this point. Initially the egg will look clear apart from the air cell which you'll see at the 'fat' end of the egg. As time goes by you'll notice this air sack become larger and it's here the chick will eventually hatch.
From day 2 to 3 you'll be able to see the yolk of the egg. When I first saw this, I was hugely excited - I thought it was the embryo. That's how much I knew.
From about day 4 or 5 in a properly developing egg you'll start to see tiny spider like markings appearing in the yolk area when you candle your eggs.
These are easiest to see in white or light-coloured eggs - in a dark-coloured egg like a Marans they're much more difficult to spot.
This is the start of the embryo's visible development. The 'spider legs' you can see are the embryo's blood vessels, which will become much more well-defined over the next several days.
The next few days see the development of the blood supply to the developing embryo, and the eye becomes far more prominent too.
If you look closely, you can see the outline of the embryo developing - it looks like a darkish ring around the eye.
Also notice at the bottom of this picture that the air cell has started to get a little larger. This too will become more obvious with time.
In a lot of ways, the first week is the worst. Once it's over you can see your chick developing and you'll also be able to tell whether you have eggs which are infertile and not going to develop.
Next week, we'll watch as the chick develops even more, make sure we're keeping the right conditions in the incubator, and learn what to do with eggs that are just not developing.