The original Book of Mormon text has examples where the relative pronoun modifying time is either which or that rather than the expected when. Here in Alma 13:1, the 1840 edition introduced the when (probably as a result of Joseph Smith’s editing). The when was introduced into the LDS text in the second printing of the 1852 LDS edition (as a result of consulting the 1840 edition). The 1908 RLDS edition restored the original which (the reading in 𝓟) to the RLDS text. The critical text will also restore the original use of which here in Alma 13:1. See the discussion under 1 Nephi 19:2 for other examples of this usage as well as the evidence for its textual acceptability.
Summary: Restore the original use of which in Alma 13:1 (“I would cite your minds forward to the time which the Lord God gave these commandments”); such usage can be found elsewhere in the original text of the Book of Mormon.