how long for them to hatch?

[silkielover1731]

my moms friend told her that you can use refrigerated eggs from your hens to hatch with...so my question is how long can they stay in the fridge for them to still hatch?
thanks in advance,
silkielover1731

 

[silkielover1731]

also another question..........for 1 gallon of water how much apple cider vinegar do i put it? i havent had chicks in a while and i forgot the measurments lol