I have a problem creating the data structure. The time I think will be constant, but that could change in the future.
That's a very important distinction. if the dt varies over time, you need an xy graph and much more complicated data structures. If dt is constant for a given run, all you need is a chart.
Here's using an xy graph, allowing for variable time increments.
This is just a quick draft. Note that the data structures grow without limit, so you need to implement measures to prevent eventually running out of memory or slowing down due to memory allocation overheads.
(note that also the "build xy graph" express VI could be used, but I don't like express VIs)