Starting a club nobody asked for is a risk. So is waiting for someone else to start it.

Only one of these gets counted as a risk. Starting the thing has a visible downside: six people show up, or nobody does, and you were the one whose idea it was. Waiting has a downside too, but it never arrives as a decision, so it never feels like something you chose. It just ends up as a year where the thing did not exist.

Find the teacher most likely to sponsor it, ask for a room and a weekly slot, then tell five specific people rather than posting it widely. Five who turn up beats fifty who saw it.