Arcana Coelestia #8790
8790. 'And they will be ready by the third day' means [thus] full and complete preparation. This is clear from the meaning of 'being ready' as preparation through sanctification, dealt with just above; and from the meaning of 'the third day' as a state made complete, dealt with in 7715, thus full and complete preparation.
Arcana Coelestia #7715
7715. 'Three days' means a state made complete. This is clear from the meaning of 'three days' as a state made complete, dealt with in 2788, 4495. By a state made complete one should understand an entire state from beginning to end; for every state has its beginning, stages of development, and highest point, this period being what one should understand by a complete period and what is meant by 'three days'.