How to sort the data displayed by UI_Tablet by the value of a column?

You can send sorted data to ui-table.
But if you like to use the sorting feature in the column headers you have to dig in deeper:

This should give you a starting point

You have to use an inject node to send a message on start with the config json in msg.ui_control. The field Parameter has to match your property definition (timestamp). You only have to send the parameters you like to change. (More information in the examples)