Now is probably not time to be ferting A palm's in your 'zone'. If other trees are starting to go dormant, then forgo ferts until Spring. Read up on dormancy and ferts and you will understand. It would not really harm anything to go with ~1/2 strength typical 'balanced' fert, like 10-10-10, or 20-20-20 or such; as long as those numbers are fairly even then one dose is not big deal, nor will it help much either
If the leaves are turning-color-for-Fall, then tree is going to sleep (basically).
What is "tree is graphed"?? That's a new one to me.....
The issues with that particular tree are the graft bulge and that there are huge internodes 'down low' which is where you want 'em tight for future development. Plus, iirr, that particular type tree is 'fast-growing' which makes ramification rather hard - it'll always look gangly when kept smallish in 'bonsai style'. You are picking a VERY difficult start here, and just being honest with you
I just don't want you to think that that tree will be a tight compact 'bonsai'; its not in the genetics most likely.
A suggestion: let it go dormant in pot, then 'plant' it in-ground while spreading root ball out, possibly over a tile' to get experience on playing with root balls. Let tree grow for a few years with trimming as needed, etc. Read up on airlayers and debate whether you want to separate tree off of that graft.
You mention 'distant' future as being Fall '09. That's more like 'next season' - 'distant future' in tree terms in more like 10 years from now
Just saying that for perspective....