When i turned 30, I put my first free point into arrow bomb, and then I maxed mastery up to 19 right away. I think its important to get mastery up before you put points into booster/soularrow/etc. My preference, at least.
I'm planning on putting my mastery from 19 to 20 when i turn lvl 119-120.
My 3rd job build is going to have an extra point...i guess i forgot to mention that.