That depends entirely on what the three different timestamps are, and what information you are trying to impart to the viewer.
If they are the start, midpoint and end of some process, and you want to show how long the process is taking, then perhaps the average durations of the two segments is what you need to plot. Or perhaps you should throw out the middle segments and just plot the overall duration.
If they are the top n times in a race, then maybe the n times need to be plotted as n different horizontal bars, sorted into ascending order.
If they are n different readings that happen to be on a single record, then maybe each one needs to be broken into its own record and plotted as if it had been n records.
So, what are the times representing?
