Now you need to make sure they're stored safely to keep them as healthy as possible until you're ready, so that they have the best possible chance of hatching.
Let's make like a hen!
In the wild, a hen will lay several eggs before she starts sitting on them - sometimes as many as twelve. To her, incubating one at a time makes no sense.
So, as hens can only physically lay once each day, her clutch can be several days old before she begins to incubate.
What can we learn from a broody hen?
As with everything in hatching, our aim is to reproduce as closely as we can the way a hen will instinctively behave until she's ready to hunker down and start incubating.
Here are 5 pointers, learned from learning about chickens in the wild, watching my own hens, and my own experience in successfully hatching several clutches after transporting eggs from the UK to my home in Italy.
One of the most critical issues for hatching is to avoid contamination with bacteria. By choice a hen will use a quiet, clean place to set her clutch.
If you're storing your fertile eggs for a few days before incubating, copy that instinct.
Although you won't be able to see it, bacteria can lurk in storage containers. Unless you're careful with hygiene, you run the risk of contaminating your current clutch.
If you're storing your fertile eggs in standard cardboard cartons, make sure they're new - don't use them for more than one set. Mark them "Fertile eggs - not for eating"!
If using plastic or resin containers, wash thoroughly before use. I use a baby-bottle sterilising liquid but a mild bleach solution is fine. Use one teaspoon of bleach to one litre (about one quart) of warm water.
A container like this one I use is ideal. It's strong, reusable and easily washed. After incubation it can be used to store eggs for eating.
A hen will keep her eggs lying sideways, and that's the way smaller incubators like the Brinsea Mini Advance (my favourite incubator) also work. But if you need to store them beforehand chances are they'll be kept on end, in a container like this one.
If that's the case, always store with the more pointed end facing downwards, even if it's only for a short time. This makes sure the yolk stays properly suspended.
It's the way they should be set in the incubator, too.
If the more rounded end faces down for too long there's a danger that the air cell will become dislodged and the developing embryo will die.
She knows instinctively that she has to prevent the embryo sticking to the membrane inside the shell.
So we need to do the same.
If you're storing your fertile eggs in a container, just turn the whole box upside down - no need to turn each one individually.
Make sure you mark the container so you know which side is which: a simple '1' and '2' will be fine. If you're likely to forget whether you've turned them or not, mark them something like 'morning up' and 'afternoon up'. That way, you know which side should be facing upwards at which point in the day.
Remember: if your eggs are smaller than the container you'll need to use packing to make sure they don't break when you turn them. Food grade tissue paper is a good solution.
A hen knows instinctively that an embryo won't start to develop until she sits on her clutch and they reach a specific temperature. So we need to keep our own 'clutch' of fertile eggs cool and make sure they don't get wet.
This is really a question of balance. Wherever you store your eggs, their fertility will be best maintained if they're cool - but not too cold - and dry - but not too dry.
Look for somewhere in your house that's not heated and not humid. A garage or a dry basement or cellar is ideal, particularly if it's got a concrete floor. The ideal temperature is between 5º and 10º Centigrade (40º to 50º Farenheit).
Whatever you do, don't store them in your refrigerator - it's too cold and the air is much too dry. In dry air, eggs will lose moisture through the shell, particularly if they're small bantams or have particularly thin or porous shells.
I've found a good way of storing fertile eggs in just enough humidity without them becoming too wet is to keep them in a carton and seal the carton inside a plastic bag.
If your chicks-to-be have arrived by post, or if like me you've carried them long distances, they will need to settle and come to room temperature before you set them in the incubator.
At least twelve, preferably 24 hours is adviseable. Wherever possible, begin incubation immediately after that.
Advice about how long eggs will remain fertile varies. In reality, the longer they're left, the less fertile they become.
If they're kept in ideal conditions, some authors - Gail Dammerow, for example, in her wonderful book "Hatching and Brooding Your Own Chicks" - considers it possible that they will remain viable for up to three weeks.
My own experience has been that after ten days to two weeks, fertility drops.
I've never been able to hatch successfully after that length of time even when I've done everything possible to keep them safe and stored correctly.
But it's always worth trying!
Before that, though, there are a couple more stages to go through: candling to choose the best quality eggs, choosing the right equipment and setting up your incubator.
The articles at this link will walk you through those steps.