Matsya Purana 264.26

264.26

athavā saptarātrantu kāryaṃ syādadhivāsanam.
evaṃ satoraṇaṃ kṛtvā adhivāsanamuttamam.. 264.25

Preliminary ceremonies (Adhivâs) of images should be observed for three nights, one night or 5 nights, or 7 nights as the case may be—24 25

Thus finishing the gateways and Adhivâs ceremonies the bathing ceremony of the Mandal should be performed in the second, third, or fourth period—26