If your instructor has a specific outline format that you are supposed to follow, then follow that. I always tell my speech students to place their "attention getting" device at the very top of the outline. Generally, this is the first one to two sentences that will be spoken, and they are specifically designed to grab the audience's attention. It could be a question, or it could be a bold statement that gets the audience emotionally charged. The attention grabber should be followed by the key things that you want to say in your introduction. From there, move into the heart of your outline. Because it is a demonstration speech, the majority of your speech is going to be explaining the steps needed to make the origami heart out of a dollar bill. I recommend including what materials are needed before moving into each step of the build.
My recommendation to all of my speech students when it comes to writing an outline is to make their outline a keyword outline. A keyword outline allows for much greater flexibility when it comes to reorganizing the speech and the delivery itself. There are a few advantages to a keyword outline. First, keyword organization doesn't allow you to memorize entire sentences or paragraphs. They don't exist. What you are memorizing for the speech is the order of content. You should rehearse the speech, and there will be sections that end up being identical, but practicing from a keyword outline doesn't lock you into a specific way of saying something in the speech. Second, a keyword outline allows you to look at a much more simplified version of the speech if you get stuck or lost during the delivery. It's much easier to figure out your location when looking through lines of keywords instead of dozens of words per line in a sentence outline.
I have another recommendation for the outline, provided your instructor will allow it. Between major speech sections, I would write down the actual transition word or statement that you plan to use in the speech in order to move from step to step in the demonstration. The risk of not planning this out ahead of time is a speech that uses the same transition word ("next") each time. If the origami heart is a 25 step process, and you say "next" each time, then the audience is going to start counting how many times you say that word. Vary your transition statements. "Next," "step 5," "after you have that completed," etc. all keep your verbal flow from growing stale.