Setting up branded tracking links for email

Hello Community -

For unknown reasons, the email tracking links were not set up for my company's Marketo instance. I am looking to get this set up ASAP but was wondering if I need to proceed with caution. Will setting up the email tracking links now have any affect on past emails or emails that are currently being triggered and sent? Is there anything I need to update to ensure that these emails will not be affected?

Thanks.