I’m a big fan of doing demos on the fly. Fire up the compiler, and show people what you’ve done.
They are meant to be exciting, exhilarating and the best forum in the world to get feedback on how you are doing.
Whether you plan it or not, you should always show up ready to go. If you aren’t ready to go, push it off, an hour, a day (no more than a day) but deliver it.
Tell the story of what you are building, show the value of what you’ve created.
If you need to plan it out, go for it, write down the points you need to cover if that helps.
But don’t show up saying – “here it is” and expecting everyone else to demo it for you.