"Then if anyone says to you, ‘Look, here is the Christ!’ or ‘There he is!’ do not believe it"
I'm skeptical of all the hoopla on the web about the alleged Rev 12 "Sign in the sky" on Sep 23, 2017. Astronomer Dr. Danny Faulkner gives us the facts in the video above and I agree with his perspective. (In contrast and truly significant though [I believe] are the two total solar eclipses in 2017 and 2024 that crisscross America and are spectacularly visible to all in the sky, not restricted to a computer screen with special software.)
The Christian part of the web is unfortunately full of lunacy and conspiracy theories, somewhat reminiscent of the warning of Jesus to be wary of such claims. Google "Nibiru" and search the term on YouTube and you will find a plethora of articles and videos, many produced by professing Christians, of a rogue planet supposedly set to make a cataclysmic appearance on Sep 23 (it was also supposed to appear in 2012). Hogwash - see here and here. As one comment on a Nibiru video sarcastically observes, "The most amazing fact about Nibiru is that it is only visible in YouTube videos." Christians that spread this kind of fallacy do nothing but hurt their testimony and take the focus off real truth. Last year, I wrote here that sometimes Christians are sadly the most gullible ones. Prov 14:15 has something to say on the subject: The simple believes everything, but the prudent gives thought to his steps.
Be ready and live each day as if the Lord might return that day, but prepare for the long-term. I hold to a pre-wrath rapture position (see here) which would not happen until we are well into the Tribulation and the church is under severe persecution.