Remember, there isn’t a “right” way to do this. But I am sharing my experience in hopes it can help.
I apply the glue with my page on a scrap paper so I can get glue all the way to the edges.
But even then the glue dries quickly so I often have to touch up the edges.
I just try to center the pages with a bit of a gap in the gutter. Some are straight..some are not quite straight. Perfection is not my goal. Learning from the spirit is, and perfect pages aren’t necessary to reach that goal.