If I understand correctly, history as we know it will end when Christ returns. The final judgment will be passed; all people still living will enter into their destiny (Heaven, Hell or Purgatory). I think the resurrection of the body will also occur at that time. Or, I’m not clear on this point, maybe that will occur later when all the poor souls in Purgatory have completed their purgation - at point Purgatory will cease to exist, having completed its purpose; and there will be no more temporal existence, all souls being either in Heaven or Hell.
At any rate there are no procedures to be followed, no prayers to be recited, when Christ returns. And no, the churches won’t be packed - we won’t need them any more. Those things belong to this life, to this Earthly existence; all of that will be over when the Lord comes again.