Next summer or earlier. The first Republican Debate last time was May 3, 2007. 90 minutes long, was on MSNBC. Here was who was in the debate: Brownback, Gilmore, Giuliani, Huckabee, Hunter, McCain, Paul, Romney, Tancredo, T. Thompson. 10 candidates by May 3. Fred Thompson and Alan Keyes announced later.
Most candidates, if not all, will wait until after the November elections. Between November and the spring most candidates will announce.
Thanks for the data, TF. That gives us a preliminary schedule of sorts to think with.