Chances are as the season goes on those birds will spread out a little more but I would hunt that field right away opening morning. Setup in a blind right in the field, if you use your decoys have them facing your blind as turkeys like to face other turkeys and this may bring them in closer. Call every once in a while but be patient. I killed two birds out of a field that sounds similar to what you are talking about last year and they didn't come in till 9 or 10 am. Get out there well before sunlight but be willing to stay out for a few hours. The funnest thing about turkey hunting is getting to learn from the turkeys themselves. I dont know if i've been much help but I hope so. Good Luck!!