To view the website before the nameserver update, you will need to install the domain prepropagation application pack for the required website. Please follow the below steps for the same after logging into helm:
1) Click on 'Domains'.
2) Click on your domain name.
3) Click on 'Application Packs'.
4) Click on 'Prepropagation Support'.
5) Click on 'Install'. After successful installation, you will be presented with a temporary URI that you can use to view your website before nameserver updates.