Charles Ellicott Commentary Ezekiel 43:18

"And he said unto me, Son of man, thus saith the Lord Jehovah: These are the ordinances of the altar in the day when they shall make it, to offer burnt-offerings thereon, and to sprinkle blood thereon." — Ezekiel 43:18 (ASV)

In the day when they shall make it.— This looks to the future, and implies that the whole structure of the Temple, and its acceptance by the manifestation of the Divine glory, though necessarily represented in the vision as already done, were still in the future. The phrase, “in the day when they shall make it,” is intended only to require the consecration of the altar before it is used. The actual time occupied by the consecration (Ezekiel 43:25–26) was to be seven days, as in Exodus 29:37.