The first results expected are for American Samoa, but with only 3 delegates at stake, the pundits will have a hard time extracting significance.   The results will be rolling in through into Wednesday morning, first states will be those where one candidate has a significant advantage in the exit polls and where this is clearly corroborated by 5% plus of actual results coming in from the state.  

The 'big three' polls close on Wednesday morning in GMT time...
Illinois - 1 am
New York - 2 am
California -  4 am

California will be the crunch, but it might be a while before the results come out as there are reports in the California media of some problems with the voting and counting operation.  Also, around 22% of the electorate will cast absentee ballots that wont be counted until days later, so there may be an even longer wait if the counting is close.

Based on watching all the recent primaries, CNNpolitics.com is the best place to get up to date information throughout the night - the website updates before they update on the TV, and it is ahead of any of the other websites I have found.    For analysis during the night, The Fix blog on WashingtonPost.com is good, as is TPM Election Central

If anyone has any other timings for results etc, or tips for watching, would be interested to hear