In most cases, maileo service is activated shortly after the order is accepted. Once the service is active, you can begin applying DNS records and preparing mailbox accounts.
Keep in mind that mail service activation is separate from DNS propagation. Even after the account is live, the internet may still take time to see the new MX, SPF, DKIM, or other records needed for normal mail flow.
For the smoothest setup, apply the DNS records as early as possible and test carefully before you depend on the service for important email.