CC Madhya 1.22

aṣṭādaśa-varṣa kevala nīlācale sthiti
āpani ācari’ jīve śikhāilā bhakti
Word for word: 
aṣṭādaśa-varṣa — for eighteen years; kevala — only; nīlācale — in Jagannātha Purī; sthiti — staying; āpani — personally; ācari’ — behaving; jīve — unto the living entities; śikhāilā — instructed; bhakti — devotional service.
Translation: 
For eighteen continuous years, Lord Śrī Caitanya Mahāprabhu remained at Jagannātha Purī and, through His personal behavior, instructed all living entities in the mode of devotional service.