Depends of what you want to aim for. If you want to be a "hybrid" archer until you retire at 31, go 18/18, with WM, PS, PD, ATHL maxed out, 50 wpf in 1h, the rest on archery. But if you want to be level 32+, go 18/21 at 30, then 18/24, with PS maxed, same goes for WM and athl, also, note that you can't be below 6 athl as archer, or you won't be able to provide a good footwork for your stabs. Forget IF and put it if you ever reach the level 34 with it.