approx. 20 days is the life span of most eggs in a cool temp say 50 to 70 if they are fertile if not they will do you no good.
After 10 days there still good but think of them as Bananas there is a span of time that there at there prime and then there is a decline from there other words your chance of the egg hatching drops.
Between 5 and 15 days is the time period I would shoot for if able but there are people here who work on a completely different method and would offer you different advice.
I only give advice from my experience from Incubating chicken eggs but I normally get a good hatch rate.
This will be my first year with turkey eggs from my red Bourbons.
Unless you a have a tried and true Broody Hen that you know is a good mother you will be taking your chances but of course you never know till you try right.