If by baldīkṣā you mean initiation into monkhood at a very young age, the Jain texts most often cited are these:

1. Vyavahāra-sūtra

This is one of the main Śvetāmbara Cheda-sūtras. It regulates monastic procedure, seniority, discipline, and qualifications in the mendicant order. Later tradition uses it when discussing who may be initiated and how monastic rank works. ( jainpedia.org)

1. Bṛhatkalpa-sūtra

Jainpedia notes that the Vyavahāra and Bṛhatkalpa belong to the oldest Śvetāmbara canonical books and together deal with monastic regulation. These are important when arguing that Jain monastic life has long had formal rules for initiation and conduct. ( jainpedia.org)

1. Kalpa-sūtra

In Jain tradition, the lives of the Tīrthaṅkaras are presented as examples of renunciation; Jainpedia says the Jinas’ lives in the Kalpa-sūtra describe how, while still princes, they leave worldly life and renounce the world. This is often used as an ideal for early renunciation. ( jainpedia.org)

1. Uttarādhyayana-sūtra

Jainpedia lists this as a major Jain text of general teachings and examples, beginning with vinaya (modesty/good conduct). It is commonly used to support disciplined, early spiritual training and renunciation ideals. ( jainpedia.org)

1. Daśavaikālika-sūtra

Jainpedia describes it as a major mendicant text containing rules for monks, especially alms-begging and ascetic discipline. It is used more for monastic conduct than for explicit age rules, but it is part of the scriptural framework cited in dikṣā discussions. ( jainpedia.org)

1. Āvaśyaka-sūtra

Jainpedia identifies this as a liturgical text describing the six daily obligatory rites of a mendicant. It is cited because dikṣā formally enters a person into mendicant life and its daily discipline. ( jainpedia.org)

Important point: Jain scripture more strongly supports the ideal of renunciation and the discipline of monastic life than it gives a blanket endorsement of child initiation in every case. In practice, different Jain traditions and ācāryas have differed on the acceptable age and eligibility. ( jainpedia.org)

If you want, I can also give you the exact Sanskrit/Prakrit verses or passages commonly quoted for baldīkṣā.