Time at which the user gave the kudo via rest API.

For a given message id, you can make a call like the following to get all the users that kudoed the message, along with the time they gave the kudo at:

messages/id/119219/kudos/givers?restapi.response_style=all

 The key is to add the restapi.response_style=all parameter, which will cause the <time> node to be included in the results.

You could use a Studio endpoint to make this call for each of the results of your users/id/43/kudos/given/messages/recent call.