Relying on charts to plot a timestamp is inherently flawed. In my opinion, charts altogether are inherently flawed, except for "quick and dirty" troubleshooting, or where the time component of the measured signal is irrelevant (uncommon). With Charts, each subsequent point is assumed equally spaced, which may be a decent assumption for short periods of time with a deterministic data acquisition.
Instead, use XY Graphs, which allow for arbitrary point spacing in both X and Y directions. This means that over time, error in time measurement does not stack up, but instead always properly represents the absolute time and relative spacing between points.
To show the X axis as a timestamp, right click the XY graph to access the properties of that graph. Go to a tab that says something like "Scales" (I don't have LabVIEW in front of me) and then choose the X-axis scale from the Listbox. Here, you can set the Display Format of the numeric to be shown as an Absolute Time, and you can customize how this time is displayed.
I'm a bit surprised anyone would condone using a Timestamp on a Graph, and I would not recommend this practice when timing is relevant.
