Ok,
your on the heavy side,
but I think you still won't need to run any air pressure,
let any air out of the fork when you get it,
check your Sag, My suggestion around 40m area +/- 5mm is good (when standing in the attack position, not sitting) if it's not enough, well you might still have air in there, or the fork has the hard springs in it.. ?? unlikely.
if it's too much, you might need some air in the fork, 45mm sag is ok if you like a dh setup fork.
once you got sag sorted, wind the compression all the way out, till it has a light stop, wind the rebound out, wind it in 10 clicks.
out in the street give the fork a few good cycles, check the rebound on each compression, make sure you do DEEP compressions, set the rebound faster or slower as required or prefered, my suggest keep slowing down till you beat the fork on rebound when you pull back, then go faster 1-2 clicks.
Now it's time to get out on your "favorite" track, go to one that has plenty of drops, roots, ruts and some pedaling. take note if the fork is stable enough for you, if it seems too fluid you might need to change to a heavier oil, unlikely this is the case, if so let me know and I'll run you through it (obviously vice versa applies).
Do some big drops and jumps at least the biggest your capable of, if the fork is bottoming harshly, or when your not making a total screw up of a landing, then start cranking in the compression, it operates only at travel end, so it will resist bottoming, go in 5 clicks at a time till you get to around 15-20 clicks then just take it in 1-2 at a time, till you get the right amount of bottom out resistance. If you get to 25clicks out of the 30, it might be neccessary to increase the oil height, or change to a firmer oil.
If with the compression damper wound all the way out, you cannot bottom out the fork, then there is too much oil in the fork for your weight, you will need to take some out, and or as well change to lighter oil (unlikely).
I set my oil height so I can bottom it out fairly easily with the compression adjuster all the way out, then adjust the compression to suit.
If you need more stability, higher oil height and or higher oil viscosity like 10wt will help out.
Personally at the moment I'm running 10wt in the compression side and 7.5 in the rebound, with a fairly low oil height, I'm still in testing, but I'm looking to go 10wt both sides, since adding 10wt to the rebound side gives more low speed compression damping (10wt has little effect to low speed compression damping in the compression side since damping is virtually disabled on that side till the last few inches)
it takes a bit of fiddling around to get it how you want it, most people will just ride it and play with the adjusters till they get it roughly right, the is much more to be had from the forks if you play with oil height and weight.
My suggestion is to avoid air preloading alltogether. It doesn't make the fork feel good in any way unless you are a tremendously heavy and harsh rider.
regards
Juls