As far as Kṛṣṇa's transcendental pastimes are concerned, they are mostly executed during the kaumāra, paugaṇḍa and kaiśora periods. His affectionate pastimes with His parents are executed during His kaumāra age. His friendship with the cowherd boys is exhibited during the paugaṇḍa period. And His friendship with the gopīs is exhibited during the age of kaiśora. Kṛṣṇa's pastimes at Vṛndāvana are finished by the end of His fifteenth year, and then He is transferred to Mathurā and Dvārakā, where all other pastimes are performed.
Śrīla Rūpa Gosvāmī gives us a vivid description of Kṛṣṇa as the reservoir of all pleasures in his Bhakti-rasāmṛta-sindhu. Here are some parts of that description.
Kṛṣṇa's kaiśora age can be divided into three parts. In the beginning of His kaiśora age—that is, at the beginning of His eleventh year, the luster of His body becomes so bright that it becomes an impetus for ecstatic love. Similarly, there are reddish borders around His eyes, and a growth of soft hairs on His body. In describing this early stage of His kaiśora age, Kundalatā, one of the residents of Vṛndāvana, said to her friend, "My dear friend, I have just seen an extraordinary beauty appearing in the person of Kṛṣṇa. His blackish bodily hue appears just like the indranīla jewel. There are reddish signs on His eyes, and small soft hairs are coming out on His body. The appearance of these symptoms has made Him extraordinarily beautiful."
In this connection, in the Tenth Canto, 21st Chapter, 5th verse, of Śrīmad-Bhāgavatam, Śukadeva Gosvāmī tells King Parīkṣit: "My dear King, I shall try to describe how the minds of the gopīs became absorbed in the thought of Kṛṣṇa. The gopīs would meditate on Kṛṣṇa's dressing Himself just like a dancing actor and entering the forest of Vṛndāvana, marking the ground with His footprints. They meditated on Kṛṣṇa's having a helmet with a peacock feather and wearing earrings on His ears and yellow-gold colored garments covered with jewels and pearls. They also meditated on Kṛṣṇa's blowing His flute and on all the cowherd boys' singing of the glories of the Lord." That is the description of the meditation which the gopīs used to perform.