I want to get the time when a user starts inputting something into input boxes.

document
    .querySelector(".InputText")
    .addEventListener(
        "input",
        () => Qualtrics.SurveyEngine.setEmbeddedData("first_input_time", Date.now()),
        { once: true }
    );

ahmedA thank you for your response, but doesn't that just save the very first time I enter something into the InputText?
I want to make sure I save the first time I enter something into each textbox (of which there are two, but both are somehow joined together into a single ".InputText", and I want to name the two different times with different variables), so I think I should be having two different setEmbeddedData calls?

In other words, I would like to get the time and store it whenever the user switches between two text input boxes.
Is there a way to use choiceId along with .InputText, maybe?

Okay.
This was assuming only one input text box. I would then recommend using ids instead of the inputtext class.
Just Google how to find the ID of an element, change queryselector to getelementbyid, duplicate the event listener and you should be sorted.

ahmedA From my search it seems you'd need attr('id') used on jQuery(#____), but I'm not sure what follows the hash, since I still don't know how to query select for a specific input. could you help?

I thought perhaps what I saw in the spreadsheet would be the id, and tried this, but that doesn't work, either.
document
.getElementById("Q36_3")
  .addEventListener(
    "input",
    () => Qualtrics.SurveyEngine.setEmbeddedData("input3_time_fruits", Date.now()),
    { once: true }
  );

Preview Survey --> right click on text box --> select inspect --> in the inspector you'll see id="...."
Use this id value inside getElementById. Also, you'll need one for each text box.