Broccoli: Floret looking delicious

About 10 days ago, I noticed there was a small floret growing in the center of the broccoli plant. In just this short time, it has grown and looks like it is almost ready to harvest.

The floret is now peeking out over the rest of the leaves and is clearly visible. The stem is almost 8cm long, and the floret is about 3cm across.

The base of the plant is still worryingly thin, as you can see in the picture on the right.

Also, there is only one floret growing. I expected a few growing simultaneously like branches. Will harvesting this one encourage the growth of new florets, or will it mean the end of my broccoli? I'll find out soon, I think.