Just ordered a set of 4K/8K/16K Shapton Glass stones. I know I need to lap them & chamfer the edges before the first use.

Here's the thing: I hate lapping stones. I don't know how people use them. They take soooo long. I've tried the Norton and Naniwa lapping stone on both my Norton 4K/8K and Naniwa SS 12K. I've found it's 10x faster/easier just to throw some sandpaper down on my kitchen counter and be done with it. The weight of the stone plus a little elbow grease will knock them flat in no time.

I've been using 220 grit sandpaper. Is that sufficient for Shaptons or should I use a coarser or finer grit?