I usually don't. I only did so once, when I wrote something completely different from what he's used to seeing from me (it was a fluffy, lighthearted contemporary romance as opposed to my usual grim, murder-filled books). I showed him the first chapter because I was so nervous about writing something so different. He loved it so, so much, and at first I was elated, but then as I continued writing, I couldn't help thinking, WHAT IF THE REST OF THE BOOK IS A LETDOWN. But if he hadn't loved the first chapter, I would've given up on the MS, so showing my agent unfinished work is kind of a lose-lose for me. I won't be doing that again unless there's a solid reason why I need to.