From what I have read, Farmhouse Cheddar is ready to eat after one month of aging.
Stirred Curd is the next earliest to ripen at 3 months and then traditional cheddar is the variety that requires the longest aging period.
I'm not positive but I think I got this information from both the schmidling website and the Cheese Wizard website.
Anyway, I've tried a farmhouse at the 6 week mark and my kids proclaimed it an excellent cheese. Personally I found it to be a little soft but it did have a nice flavor.