8 (7 if you skip nukes, didn't read your build until post-post (AHAHAHAHA))
But you might as well go 5 and farm at 9 later, 8 gapping is a waste of time, as monster hit points jump at some gaps and you'll need a stream of nice weapons rather than just one degree.
thats easier said then done
but a god idea
i wanted to get 2 30 fast for nukes but now im paying for it because i have basically no sp 2 keep up with skills so ive got a 4 lvl gap and probly goin higher because i didnt farm.
the way i do it:
9 gap at 30-35ish (get a good 29 and 32 weap and go to horses...WIND 4!!)
9 gap at 44-5x (depends on how much u need. bunwangs for wind 2/4 and then mujigis for str or shades for int)
most of my friends say 4-5 gap is enough for them but they are mostly str chars and int tend to need a lot more farming cuz they need updated skills, nukes, and buffs to optimize their grinding
that usually covers just about everything u need.
BUT!!!!
if you prem/gold tix and gold sp tix the whole way...u can be fully farmed to 80 on only like a 2-3 gap. (you would get 200k or more sp on a 0 gap but most of the sp u get would come from 70-80 which means u wouldn't be fully farmed while ur trying to get to and through those lvls. thus...the 2-3 gap)