Got it! For anybody wanting to implement this on your shop, I edited the tpl_modules_downloads.php file in includes/templates/my template/templates and added:
Code:
<?php
$purchase_date = $downloads->fields['date_purchased_day'] ;
$todays_date = date("Y-m-d");
$today = strtotime($todays_date);
$available_date = strtotime($purchase_date.'+ 1 day');
?>
and then served up the download link with an if else statement like so
Code:
<?php if ($available_date <= $today) { ?>
<?php echo '<a href="' . zen_href_link(FILENAME_COUPON,'order=' . $downloads->fields['orders_products_download_id'] . '&id=' . $i, NONSSL) . '">' . zen_image_button(BUTTON_IMAGE_DOWNLOAD, BUTTON_DOWNLOAD_ALT) . '</a>' ;?>
<?php
} else { DOWNLOADS_CONTROLLER_ON_HOLD_MSG } ?>