When is right time to Contact a Domain Registrar in case of abuse?
In case if the domain name itself is being used for illegal purposes, such as phishing scams, copyright or impersonation etc., it is right time to notify the domain registrar.
Finding the registrar is easy. Just look for this line in the Whois record (you can use whois command in terminal or whois web-site):
Registrar: EXAMPLE REGISTRAR