Many hosts will give you a temporary URL to view your website.
Sadly however this causes a lot of problems for you when trying to then make your website live if you built it around this temporary URL.
When you receive your welcome email you will be given the IP address of the server that your account is on.
If you wish to view your website, then just add your IP and domain name to your computer's hosts file and reboot if needed.
Alternatively, you can park a spare domain name in your cPanel and use that temporarily then switch the domain over when ready to go live.