Oh my goodness!
I have read regularly not to use up my dining reservations on the first night as there are plenty of tables available and you can book as soon as you walk on the ship. I did not mean that you cannot book.! We did. We had all the confirmation necessary as proof! I made reservations from my home at 1am, months and months before our trip.
We arrived at 7.25pm. Not late.
“just ask at embarkation” means exactly that. Again I have read many times that when you embark the ship, choose which restaurant you would like to eat in on the first night, make the booking.
Hope that’s clear!