Go for it. Make it fun. Don't assume anything. Just play. Get some pheasant wings from gundogsupply or someplace and use them as "special" play with high praise and quick reward--diminishing to occasional reward to taking out the wing is reward in and of itself.
My GWP, Young Bert, was over two before he got out of his backyard prison, and Mick, the new, used, dog, a field Springer Spaniel was four or five before I got him from rescue. YB was a wonder, and Mick is in love with hunting and retrieving my meager game successes.
Frozen quail can be great for eliminating a hard bite before it develops...and you can do it just sitting on the kitchen floor, where you are close enough to immediately correct the dog.
Can be great fun.
Best wishes.