Can I setup a website without a domain immediatley?
yes, but well you will need atleast one domain to start with.
If you want to setup a website without purchasing a domain, then you may want to start looking at free hosting services sites. You can get a list by conducting a quick search on any search engine.
I would like to tell you that many of those do have automatic ads that they put on your site. I generally would not even tell you to get one, especially if you are looking to make a professional site and want to earn money from the site.
You can register a domain now days for so little money, and if it does not work out then do not renew the registration. You want your site to be professional, then get your own domain, and hosting.