CC Ādi 13.31

kiśora vayase ārambhilā saṅkīrtana
rātra-dine preme nṛtya, saṅge bhakta-gaṇa
Synonyms: 
kiśora vayase — just before the beginning of His youthful life; ārambhilā — began; saṅkīrtana — the saṅkīrtana movement; rātra-dine — night and day; preme — in ecstasy; nṛtya — dancing; saṅge — along with; bhakta-gaṇa — the devotees.
Translation: 
Just prior to His youthful life, He began the saṅkīrtana movement. Day and night He used to dance in ecstasy with His devotees.