TIEro on "Action on attachment upload not detecting mime type"

I'm writing a function for a plugin that does a particular action when a new media file is uploaded, provided it is of particular types (specifically docx and doc, i.e. MSWord documents). However, it doesn't seem to detect the attachment type correctly.

I suspect this may be because the action hook (add_attachment) runs before the line is fully created in the posts table, and therefore the mime type is blank. That said, the attachment_id is available, so shouldn't the mime type be there as well?

When I upload a docx, a doc and an image, all three are processed by the function and I get three lines in my documents table... there should only be two.

The action hook is simply:

add_action('add_attachment', 'wle_record_document_upload');

The function looks like this (it adds a line to a custom table which I will be using as part of the plugin):

function wle_record_document_upload($attachment_id) {
	global $wpdb;
	$user_ID = get_current_user_id();
	$type = get_post_mime_type($attachment_id);

	if ($type = 'application/vnd.openxmlformats-officedocument.wordprocessingml.document' || $type = 'application/msword') {
		$sql = "INSERT INTO {$wpdb->prefix}wle_documents (user_id, attachment_id, status_date)
				VALUES ($user_ID, $attachment_id, NOW())";
		$result = $wpdb->query($sql);
	}
}

If anyone can see what's wrong, I'd appreciate it!