how long will bourbon hens lay fertile eggs after tom gets them?

[dragontamer56]

I am going to buy some hens from a lady and i wanted to hatch out there eggs. The lady doesn't have any extra toms and the hens will be with the toms when i pick them up and will be fertile. I was jsut wondering how long they will stay fertile after i take them from the toms.

 

[jasonm11]

up to about 15 days