Śrīla Bhaktisiddhānta Sarasvatī Ṭhākura quotes his notes from the Nāṭaka-candrikā, wherein he has written:

prastāvanāyās tu mukhe
nāndī kāryāśubhāvahā
āśīr-namaskriyā-vastu-
nirdeśānyatamānvitā

aṣṭābhir daśabhir yuktā
kiṁvā dvādaśabhiḥ padaiḥ
candranāmāṅkitā prāyo
maṅgalārtha-padojjvalā
maṅgalaṁ cakra-kamala-
cakora-kumudādikam

Similarly, in the Sixth Chapter of the Sāhitya-darpaṇa, text 282, he has said:

āśīr-vacana-saṁyuktā
stutir yasmāt prayujyate
deva-dvija-nṛ-pādīnāṁ
tasmān nāndīti saṁjñitā

The introductory portion of a drama, which is written to invoke good fortune, is called nāndī-śloka.