You can do your self a big favor by patterning your shotgun before you hunt.
It does several things.
Helps determines your maximum range. (Any good pattern at 20 yards will definitely kill that turkey - however much past that you need to really know your pattern.)
My rule of thumb is 8 to 10 pellet holes in the neck vertebrae and turkey's skull and/or eye. I do not count holes in anything but those regions.
I get consistency of 8 to 10 pellets or better in those regions and that tells me my lethal range. Any less than that I do not take the shot as this patterning determines what is not in range.
Tough thing to do you will see.
Helps determine if you have any holes in your pattern.
Gives you the confidence that once that shot is there you know you can do it.

Know your ranges - use a range finder if you have one and if not and you do have the chance, pace out 20 steps and place a stick in the ground. Then make that your goal to call the bird too.
If you can't do that. Practice knowing your ranges and practice some more.
Last thing you want to do is take the shot only to see the bird run away wounded!!! Been there done that and its not fun!
So I don't take iffy shots.......I know once I pull that trigger - Mr. Tom will be mine.

Turkey hunting for me is calling that bird up close and personal. I rarely take shots past 30 yards anymore. Actually in the 28 yrs my avg is 22 paces from where I sit.

JW