Not sure that there is a best size but I do know that most garages on builder's plans, in spec houses, and on the plans available online are way tooooo small. Typically I think they're often just 20x20.
Merriam-Webster dictionary simply says a newborn is a baby who is recently born and does not put an upper limit to the term. The dictionary also defines an infant as a child in the first stage of life but doesn't give any age specifics. The World Health Organization (WHO) defines a newborn, or neonate, as a baby under 28 days old. As the name implies, a toddler is classically defined as a child who is just learning to walk or one who toddles. This is often around one year of age. There's no official definition of the upper limit of toddlerhood.
infant, n/adj a child who is in the earliest stage of extrauterine life, a time extending from the first month after birth to approximately 12 months of age, when the baby is able to assume an erect posture; some extend the period to 24 months of age.ee also growth. large-for-gestational-age infant a preterm, term, or postterm infant who is above the 90th percentile for gestational age in head circumference, body weight, or length. low-birth-weight infant one that weighs less than 2500 grams at birth.