Here are the details I can find on the times for the caucus states:
North DakotaThe state is split between Central and Mountain time. Instructions here:
http://www.northdakotagop.org/caucus/indicate that people can show up at their caucus between 5:30 and 8pm local time, with 8pm corresponding to either 9pm or 10pm ET, depending on which time zone. It says they'll post live results starting at 8:30pm Central / 9:30pm Eastern.
IdahoCaucus locations are listed here:
http://www.idaho-republican-caucus.com/idaho-counties.htmlEvery county starts their caucuses at 7pm local time, but part of the state is in Mountain time, and part is in Pacific time, so that corresponds to either 9pm or 10pm ET, depending on which time zone.
This website:
http://idgop.org/caucus-results/says "Caucus results will be posted here as early as 8:30 pm Mountain Time", which means 10:30pm Eastern.
AlaskaThis article:
http://www.alaskapublic.org/2012/02/28/alaska-republican-caucuses-approaching/says the caucuses take place between 4pm and 8pm Alaska standard time, which translates to between 8pm and 12am Eastern.
Meanwhile all the polls in the primary states will be closing at 8pm Eastern at the latest. And caucuses tend to count their votes much slower than primaries. So it looks like there could be a big gap in the evening between the primary results and the caucus results.