If you allow them to free range on that much acreage, you may never get eggs, there is no telling what is out there beating you to fresh eggs. I agree with the posters who said to leave them in for a day or two and see what you get. If you get eggs, I would suggest building them a run vs allowing them to free-range on that much space. We have 111ac and there is NO WAY I would allow our chickens that much space, anything could happen to them. They have a huge run and we DO allow them to free range in the garden when its done for the year, but its supervised, we let them out there around 3/4PM to make sure they dont go too far before its dark at 6/7PM.
I was going to suggest adding oystershell, but that might not be the problem. I know if my EEs don't have OS, we will not have eggs. I don't know why it is like that for some breeds, but it is. They all get the same feed, but the EEs need that OS. When our feed store was out for 2wks, we didnt see a blue egg for the same time.
Our golden comets started laying about 25-27wks, our production reds at about 24-26wks and our EEs at 28-31wks(it seemed FOREVER before we had a blue egg). This was all during "peak" season as we got them in Feb/March. We had a second batch of EEs that started at 25wks(same hatchery and they JUST started-we have 4/9 laying so far, and it is off-season). The birds are all just different.
We were told by an experienced chicken keeper that the first batch of chickens always takes the longest, but once one starts the rest follow, BUT if you already have layers, the eggs come faster as the hens seem to know what to do(and where to do it). So far this has held true for our group, but Im not sure if part of it is just that we are no longer anticipating eggs like we were with the first group.
Good luck and I hope you find eggs soon!!