do you think we can also use "good day" to express having good luck?or it should become popular from now on?:p
MacMillan English Dictionary - American
,good `day interjection *
1 AUSTRALIAN SPOKEN used for saying hello to someone in the morning or afternoon. Good day is often written g'day to show how it sounds in informal conversation.
2 BRITISH OLD-FASHIONED used for saying hello or goodbye to someone in the morning or afternoon