If you are interested in maximizing the chances of finding people for a meetup, you should remove the trivial inconvenience of requiring people to voice their interest. Just set the time and place unconditionally and see if people show up, collect their contact info, and repeat (even if nobody shows up the first time). If you use something like a cafe as a venue (which is OK if you expect at most a few people, just make sure there are empty seats and no loud music), all you personally have to do is sit there for an hour (you can spend the time reading something if nobody else shows up).