Scofield Reference Notes, 1917 EditionJoshua 4

The two memorials The two memorials. The twelve stones taken out of Jordan and erected by Joshua in Gilgal, and the twelve stones left in Jordan to be overwhelmed by its waters, are memorials marking the distinction between Christ's death under judgment in the believer's place Psalms 42:7; 88:7; John 12:31-33 and the believer's perfect deliverance from judgment. The stones in Jordan stand, typically, for Psalms 22:1-8.

first month i.e. April.