Look them up in this dictionary: http://www.etymonline.com/. This will tell you when.
But the OED (oed.com) will also give you a quote:
1600 R. Hakluyt Princ. Navigations (new ed.) III. 735 An Indian boy driuing 8. Llamas or sheepe of Peru which are as big as asses.
Welcome to the forum, MrNirom. Here's what the digital OED has to say:
[1604 E. G. D'Acosta's Hist. W. Ind. xli. 319 Pacos, or sheep bearing wooll. 1753 Chambers Cycl. Supp., Pacos‥the name of a species of camel‥ known among many by the name of the Indian sheep, or Peruvian sheep.] 1811 Arcana (of Nat. Hist.) The Acalpa [sic] is another animal of Peru. 1827 Griffith Cuvier IV. 57 The Paco or Alpaca was first clearly described by M. Frederick Cuvier in 1821. 1830 Gard. & Menag. Zool. Soc. I. 278 Early travellers in America speak vaguely of the Llama, the Guanaco, the Paco or Alpaco, and the Vicugna. 1848 T. Southey Colon. Wools iv. 289 The Alpaca is about 4 feet high.
OED: 1600 R. Hakluyt Princ. Navigations (new ed.) III. 735 An Indian boy driuing 8. Llamas or sheepe of Peru which are as big as asses.
1747 J. Campbell Spanish Empire Amer. ii. xiii. 218 The Guanacos, and the Alpacas, these last yield a very fine black Wooll. (However, as these are written in italics and they probably represent the use of Spanish directly.)