Modifying a prompt

I was looking for documentation on hooks or filters and the assistant on your site basically told me to look at the code. I did.
I need to add a timestamp to the start of every prompt. I hacked this into the code (the absolute last way I want to do this, but need to test it) and it works. How can I do this properly?

function AI24AI_handle_chat_request() {
date_default_timezone_set(‘America/New_York’); // optional but recommended
$time = date(‘Y-m-d\TH:iP’);
$current_time = ‘[Time: ‘ . $time . ‘] ‘;

// Extract & Sanitize User Input
$user_input = sanitize_text_field($_POST['user_input']);

$user_input = $current_time . $user_input;