Well, ok. It sounds like a pretty good plan. I farmed at lvl 42 with a brand nwe SOS glavie. But if you want to farm at 38, fine
Actually I think you should calculate how much SP you need for a certain instead of farming with 9 gap to lvl 41/42 from 38. That will take forever.
Collect SP for lvl 80 if you are a hardcore gamer, or for like 52 if you dont want to SP-farm that long. Its up to you
I collected ~50.000 SP at lvl 42 with a glavie, so it was pretty slow. But I need to farm again soon, thinking of lvl 64-66 with a 7-9 gap somewhere in the DW caves.