It will be all over when He knows that the last person to accept Him has done so. The rest will have hardened their hearts and He’ll know that.
I believe that though some would differ and have. I am of the mind if you’ve had the opportunity to accept Him and refuse this side of the Tribulation, you’ll swallow the lie to come and won’t be able to then. But those who have not heard prior would have that opportunity then.
I say why take the chance...”Today is the day of salvation” after all!