I looked into it when I was in high school, and I didn’t find a mekor earlier than the Belzer rebbe, if i remember correctly. I think that the ??? says that one should open the door for ???? ???? to symbolize the ??? ???????, and ????? ?? i.e. the ?????, Eliyahu Hanovi should come. I don’t think he means to the ???, he means to be ???? on the ?????, bby”a.
I guess whoever says ???? ??? when they open the door is expected a visitor of some sort. Yekkes don’t say it.
And even if he does come, I do not think he drinks. But this is my opinion. No mekor.