Both reviews publish at the same moment: when both sides have written one, or fourteen days after the first, whichever comes first.
Neither of you can read the other’s review before writing your own. Publishing one first turns the second into a reply, and a marketplace where reviews are replies has no honest reviews in it.
You can reply once to a review about you, and that reply is public too.
Still stuck? Open a support ticket and a person will answer.