So this is probably a stupid question, but I just set up my first website and the site loads without issue. https://www.whatsmydns.net confirms that the A record and Nameservers have propagated correctly. However, there are no results for CNAME. Is this something I should be concerned about? Could it just be taking longer to propagate than the other two records?
General practice is to CNAME www to your root domain, so www.yourdomain.com is a CNAME to yourdomain.com. However, there's really nothing wrong with making www.yourdomain.com an A record.
Short answer, no, nothing to worry about.