Here’s what I’m referring to: I remember learning a piece from the reshimos (The Rebbes learning diary from before he became Rebbe) where The Rebbe asked why it’s necessary to await Moshiach’s coming every day, if Eliyahu HaNavi will precede him by three days. So logically, if Eliyahu hasn’t come yet, how can I expect Moshiach to come today?
The answer is that there’s three stages in Moshiach’s revelation: (trying to remember the exact lashon by heart, because Rabbeinu Bachya says similar so I’ll include both versions of the wording):
1. His first revelation/ to the ones that know him
2. Fighting the wars of Hashem
3. His revelation to everyone
And Eliyahu haNavi can come before any point in those stages, so we need to be prepared for Moshiach, even without.
So everyone can be happy now. For everyone (outside Lubavitch) it will be obvious when Moshiach is here, so you don’t have to keep fighting- you can just wait til stage 3.
For other sources on the stages, see Rabbeinu bachya who explains that כימי צאתך מארץ מצרים אראנו נפלאות just like Moshe revealed himself, and then the slavery
intensified just as Moshe Rabbeinu disappeared again, and then he came again and did the makkos, so too by the final geula this will happen and it will be a test of Emuna.
Also see the Rashi on Daniel אשרי המחכה.
There may have been other sources listed on the Reshima (or not as it wasn’t for publication) but I haven’t had the pleasure of seeing it in the original