The beginning of an EventStorming session with people who never did it before can be quite awkward. After you as a facilitator explain the rules and give people pens and stickies, then put the first element of the notation:

After this is done, there will be this moment of silence and uncertain movements in the crowd. No one knows what to do, and people are usually uncomfortable with doing something they aren't familiar with. This is especially obvious if such activity needs to be performed in front of the crowd:

This moment requires the facilitator to break the ice. This is not hard to do. When you organize such session, you already know something about the organization and the domain. This allows you to imagine some domain event, or two, or more. Bringing this knowledge to the wall is exactly what people need to lean by example. The whole thing is not hard to do, but without any case, people don't feel safe and secure. So, as a facilitator, you will need to put the first sticky note on the wall, or a few of them. Try making it relevant, or you can intentionally make them very silly, expecting people to react with laugh and sarcasm, fixing your error. Of course, the first reaction that you get is people speaking out loud what they think needs to be put on the wall, without doing any action at all and expecting you to write things down. This is how traditional meetings are done—people talk, and someone hopefully is taking notes. Resist this. As soon as you see someone explaining what you need to write on the next stickie or telling you that stuff on the wall is wrong - just give them a pen and a stack of sticky notes. They will start writing. They will produce. They will discuss. Then, your job will be to observe and to guide in case people get stuck.

There are at least two techniques that I know of on how to start the workshop by putting the first stickie note on the wall. The first comes from Alberto Brandolini. He says that you can put anything you want, anywhere you want but not at the start. Starting at the "beginning" is something you want to avoid. This is very natural for us as human beings to seek structure and in our view, each process starts and ends somewhere. So, logically speaking, we need to start at the beginning. The only issue here is that there is no beginning. First, we always spend a lot of time and energy discussing where the process starts, without producing anything. Second, there will be something before any identified start, guaranteed. Therefore, put the first sticky somewhere in the middle and work from there. Stuff that happens before that event will go to the left, and the thing that occurs after to the right:

Dan North mentioned another technique in his talk at DDD Exchange 2016. On one stickie he writes "once upon a time" and puts it closer to the left side of the paper roll, but not at the edge. On the second stickie, he writes "happily ever after" and puts it closer to the right side of the paper roll, but again, not to the edge. You need these gaps on both sides because, as mentioned earlier, there will be definitely something earlier than "once upon a time" and later than "happily ever after" and you will need space to put it there. As you can see, you need to have exactly zero knowledge about the domain to produce these two stickies, and it works quite efficiently. People get the sense of time and with something already on the wall, giving them space in between to fill out, sparks their imagination.