A different way to look at the first 100 users is that sometimes the product itself can do part of the growing for you. If people naturally have to invite a teammate, share a report, send a link, or bring someone else into the workflow, one user can easily lead to another without much extra marketing. That kind of growth might not be something you planned from the beginning, but once you notice it happening, it can be more useful than trying every channel at once. For the first 100 users, I’d pay attention to how people are already sharing the product and build around that.