From the Guidelines

The initial dental exam for a pediatric patient should be done at the age of 6.

The age of 6 is recommended because, at this age, permanent tooth buds, except those of the III molars, are visible in the panoramic image 1.
This recommendation is based on the idea that radiographic examination should only be prescribed considering the patient’s medical records, clinical signs and symptoms, and the risk/benefit of exposure to a potentially harmful radiological examination 1.
The American Academy of Pediatric Dentistry (AAPD) recommends that a child should visit a dentist by their first birthday or within six months of the eruption of their first tooth is not mentioned in the provided evidence, however, the provided evidence consistently recommends age 6 for radiological investigations for various dental anomalies, including dental impaction, numeric anomalies of teeth, dental morphology anomaly, and tooth transposition 1.
It's essential to consider the patient’s medical history, clinical signs and symptoms, and the risk/benefit ratio before prescribing a radiographic examination 1.

Level I radiological investigation is advised after the age of 6 for suspected numeric anomalies of teeth, dental morphology anomaly, and tooth transposition 1.
Orthopantomography is the indicated 2D radiological imaging technique for these investigations 1.

From the Research

The American Academy of Pediatrics and the American Academy of Pediatric Dentistry recommend that a child's first dental visit should occur during their first year of life for dental disease prevention and to decrease invasive restorative interventions 2.
A study found that the adjusted hazard ratio of dental caries for children whose first oral health examination was at 4 years of age is 5.425 times higher than for children whose first oral health examination was before 1 year of age, highlighting the importance of early dental exams 3.
Many professional dental organizations recommend that the first dental visit should occur by the age of one year 4.

A study in Lebanon found that children came to the pedodontist upon the decision of their parents, and a dental problem was the major reason that triggered the first visit, indicating a lack of preventive care 2.
Another study found that the most common reason for the first dental visit was caries and its complications, followed by parents' decision to have a prophylactic examination of their child 4.
A survey of dentists found that only 17.93% recommended that the first visit should be before the age of 1 year, and it was predominantly pediatric dentists who recommended a dentist appointment in the first year of life 4.

Early dental exams can help prevent dental caries and decrease the need for invasive restorative interventions 2, 3.
A study found that performing a clinical exam on a young child was associated with willingness to see children younger than two years of age in practice, highlighting the importance of early exposure to young pediatric patients 5.
The First Dental Home initiative encourages general practitioners to actively participate in providing care for young children under the age of 3, including infant oral exams and preventive treatment 6.