looks very good for a practice piece. Here's a few ways ive been doing them to give you some ideas.
Here's a scrap piece of 2x4 I've screwed to a basic screw on face plate. Then I glued on my handle material with CA. You can turn the hole size exactly as you need it, depth and width custom fitting the knot. have it there so you can fit it perfectly. Once your done sanding and finishing, use your parting tool to cut it off. On a flat surface, like your counter top or your wifes glass top stove, go through your grits of sand paper until the bottom is perfectly flat.
Attachment 164990
Here I have the handle stock in my Talon chuck completely sanded and finished. I could do the same procedure as above, parting tool, flat surface to sand on.
Attachment 164992
Or, I could use the tail stock to bore a hole on the inside of the handle, thread it, and mount it on a mandrel. Then flip it around and mount it in a drill head chuck so you can turn the bottom, sand it, and finish it right on the lathe like this one below.
Attachment 164995Attachment 164996
Before you glue in any knots, maybe do some reading on different lofts. Not sure what knots your using, or what you prefer for a loft height, but make sure you know what you want before you glue it in.
Hope this helps you a bit, and give you some ideas.