Think of it this way- most people over order on shipped eggs. Why? Because so many things go wrong.
Consider the breeder/Seller- you don't know the condition they keep the chickens unless you are able to go to their farm and look and even then you can't be sure. They may be feeding them something that makes the shells tough or porous. They may not actually have good fertility. They may be holding onto the eggs for longer than they say they are, which means you may be getting them older than is best for hatching. I'm not saying all or even any of these are true, but they are considerations that MAY be true.
Consider the act of shipping- your eggs depend on proper packaging to protect them from shipping. It will take at least 2 days to get to you (adding to how-ever long the seller had them on hand). In this two days they will be put through a sorter, tumbled, tossed, jostled, shaken, and otherwise abused. They may be subjected to x-ray. They may be subjected to heat or cold- and the heat may start them on incubation early. And if your seller decides putting 'hatching eggs' on the outside of the package, there's a bonus risk of the idiots of the world shaking the box to hear the chicks peep because they think hatching means the eggs are hatching in the box.
Consider incubation- Now your shipped eggs have arrived. You have no way of knowing if they started incubation so you should probably put them straight into the incubator while the weather is hot, without turning them for 24 hours. From this point on, their fate is in YOUR hands to do everything right. But nothing ever goes 'everything right'. You have to watch for temps to vary, humidity to vary... those air cells may be loose from shipping. You have to turn them right. Lockdown right. And the chicks have to actually have the strength to get out of their eggs.
Consider after hatch- At this point, you're probably down to the average hatch for shipped eggs: 30-60% of your original eggs- if you are lucky. Now you get to see who survives the first week from the hatched babies. You may lose some to not being smart enough to eat, or drowning in the water dish or eating shavings or whatever other way chicks find to die. And sometimes, they just do what is called 'failure to thrive' and they die for no explicable reason. And if they all make it, if you're looking for hens only, then you're weeding out the boys for whatever is left.
So I'd say yes, at least a dozen and if you end up with more, offer them up to friends or on BYC's buy, sell, trade area.
I'm going to give it one more try before selling my bator! I don't like this much disappointment
