i dont know about Mo.
but here in Mn. the season has been giong for a few weeks already
i dont get to hunt for 2 more weeks,but i have been doing alot of scouting and calling in the mean time
i have already noticed a HUGE decline in gobbling.
i know as the season gets further along and more and more hens are sitting on eggs the toms seem to gobble less
not that they are not interested in breeding,they just get less vocal.
but i have noticed over the years that gobbling activity can come and go from one day to the next
i have hunted early in our season and heard very little gobbling sometimes,sometimes theygobble like mad
i usually hunt late in our season,and have had the same thing happen.sometimes they will gobble like mad all day long,the next day they may not make a peep
find your self a known well used travel route and sit by it and make some soft subtle calls.dont over call,something alot of hunters do.
i find that 2-3 soft clucks or yelps about every 45 mins to 60 mins works best.the key there is SOFT calling,and seldom calling.
even better if you can find where they like to gather and be social in the morning,set up near that
good luck