The first debate came first, reports CNN's Kevin Bohn, with Romney taking part in 16 mock debates before the Denver showdown with Obama.
Beth Myers, who directed Romney's debate preparation, said she wanted getting ready to debate the president to be the "Manhattan Project" of the campaign. The first general election debate prep came in June with policy sessions because officials knew this would be a good chance to give the campaign a jolt.
There were policy and strategy sessions in June, July and August. Myers made sure Romney was armed with a research book for any cross-country trip. During the Democratic convention in early September, Romney went to debate camp doing five mock debates in three days. And for "fun at night" the aides would do whiteboard review sessions.
Romney did 16 mock debates in total because those close to him knew that one way to help him relax was to make sure he was as prepared as possible.
[Hat tip: Garance Franke-Ruta]