Good Evening Does Not Replace As-Salamu 'Alaykum
Question :
A common and widespread practice nowadays is to say "good morning" or "good evening," rather than to say the Islamic greeting.
Answer:
The greeting that has been reported is "As-Salamu "Alaykum" or "As-Salamu Alayk." After beginning with this, you may continue to give any other kind of greeting, such as "good morning" or "good evening." These greetings come after the legislated greeting. As for preceding the legislated greeting with such statements, this is wrong.
Source:
Ibn 'Uthaimin
Fatawa Islamiyah, Vol. 8 Page 217