First deciduous teeth usually comes around 6 months of age. They are:

Primary teeth generally begin to erupt at about 6 months of age. The mandibular central incisors usually erupt before the maxillary incisors. The first teeth may appear as early as age 3-4 months or as late as age 12-16 months. Ref: Klein U. (2012). Chapter 17. Oral Medicine & Dentistry. In W.W. Hay, Jr., M.J. Levin, R.R. Deterding, J.J. Ross, J.M. Sondheimer (Eds), CURRENT Diagnosis & Treatment: Pediatrics, 21e.