Don't be ashamed, I have claim to that if anyone does, turkeys have been available in huntable numbers here since the late 60s, early 70s, but I didn't start hunting them until '95 when I was almost 50!! Once I did, I just kick myself for missing out on all those years of good hunting opportunities missed!!
You're doing great!!
As dukkillr said, I too use a 3M scotchbrite pad to condition my slate calls.
I would recommend you try several different loads until you find one that patterns best at the range you want to kill at, you may find that the best load will be standard load and you will most likely need to limit your shooting to a much closer range than you'd like.
I hunted a few years with a 20ga smoothbore flintlock, because of it's cyl bore, I had to limit my shots to 15yds to be sure of having sufficient pattern density.
Tim