I started with 180. Then 400, 600, and 1500. Rubbed down with Mother's mag polish. Turned out really nice, but if I could do it all over again I would start with a more coarse grit (100?) and then find some 1000 to go between 600 and 1500.
The most important thing is to make sure all the tooling marks are gone before you continue on with finer grits. And to make sure you sand off all of the previous grit marks before going finer.
A buffing wheel would be nice to keep it touched up after polished, but a quick wipe down is probably fine. I'd definately wait to sharpen until your through sanding. You're bound to beat up the edge while sanding.
If you want a real polish it's gonna take a little while. Especially if you're hand sanding like I did. The end result is worth it in my opinion.
That 9 looks very nice by the way.
I need to do some work on a few of my Becker's. Sometimes finding or making time is tough.