Investors are slowly coming to grips with a summertime Fed rate hike, but the timing could get interesting.

Since Fed chairs started holding quarterly post-meeting news conferences in 2011, it's been the market's assumption that there would be no hikes without someone there to explain why. The test cases for that theory, however, have been scant, being as there's been only one rate rise since then, at the December 2015 meeting at which there was a conference.