I truely believe when the Bible says Satan was evil from the beginning that it is talking about creation specifically the creation of man. The devil was against mankind from the start with Adam and Eve.I see in the Bible that mankind is Satan's error. He hates man. Looking at the biggest evidence is Job. Satan is out to prove to God that man was not worthy to be created. He makes comments about mankind not just Job with disdain in an obvious effort to chalange mankind before God . I truely believe Satan fell because he disagreed with mans creation and is ever trying to prove his original point to God in order to save himself. If man utterly fails then Satan would be right. You can imagine how much he hated the God man Jesus and wanted Him to fail.