To avoid complications in resolving this market, I define an OpenAI model as announced when it appears on https://openai.com/research under "Models." For reference, here is the current list, as of March 18:

This list looks complete enough to me that I'm comfortable using it as a proxy for model announcements. However, note that e.g. GPT-3.5 would not have counted as a new model, but OpenAI Codex would have.

I may bet in this market.