most of the osage i work on are 6-10 rings per inch.
tho i have had osage with fat rings, like 3 per inch at least at one end.
even read here some time back a fella made an osage bow that the limbs ended up being only one ring, they were that thick(like 1/2"!)
but with the average, likely at least 20 yrs unless ya wanna make a simple sapling bow.
was helping a pal split a osage log about 15" in diameter. i think dale counted about 65...
and there is some osage in wash an oregon, planted back when it was planted so much in the midwest.
any chance there were osage posts shipped out west?
i'd think it would grow well there.
so either ya got 20 yrs to wait, or think of it as a contribution to other bowyers to come along after ya.
one way to keep the tradition alive.