Earlier is better. My best advice for public land is along the Platte River with some of the public options there. Unfortunately, do know that our public land is pretty heavily used. The good is that turkey are somewhat of a nuisance to a lot of farmers, and they don't care about people taking some. Don't be afraid of a knock and talk campaign, as you may find some people pretty willing. NE Game and Parks may be able to give you some tips as well if you gave them a call. I personally hunt the central and eastern side of the state and have a lot better luck than out west. My dad heard one gobbling yesterday morning already (SE Neb). I would aim for the start of turkey-shotgun season in mid April for best luck calling instead of lucky ambush.