“Guacamole” isn’t found in English-language cookbooks until about 1930. Guacamole is a Mexican dish and is called “huacamole” in Texan Ranch Life (1894). The food term comes from ahuacatl (avocado) and molli (sauce) and is often made with onions, tomatoes, chili peppers, lime juice, salt, olive oil, and vinegar.
 
 
(Oxford English Dictionary)
guacamole
[Amer. Sp. guacamole, ad. Nahuatl ahuacamolli, f. ahuacatl avocado + molli sauce.] 
A Mexican dish made from avocado pears mixed with onions, tomatoes, chili peppers, and seasoning.
1920 W. POPENOE Man. Tropical & Subtropical Fruits ii. 23 In the tropics, the fruit is added to soups at the time of serving; mashed with onions and lemon juice to form the delectable guacamale of Cuba and Mexico.
1943 I. S. ROMBAUER Joy of Cooking (rev. ed.) 38/1 (heading) Avocado Spread (Guacamole).
 
Texan Ranch Life
by Mary Jaques
London: Horace Cox
1894
College Station, TX: Texas A & M University Press
1989 reprint
Pg. 286:
The portales of the fruit market were very fine and we enjoyed the prickly pears—when they had been peeled for us. One evening in the dusk we bought some chirimollas and aguacate, mistaking the latter for figs. They were anything but pleasant, but after being dressed according to Mr. Barrow’s orders, made a nice dish known as “huacamole.” The figs and bananas at the hotel were delicious.
 
15 May 1912, Boletin de la Camara Agricola Nacional de Chiapas (http://www.paperofrecord.com), pg. 8,
col. 1:
En forma de pasta con aceite, vinagre, cebollas picadas y sal es una ensalada nacional de sabor exquisito, que se le denomina con el nombre “Guacamole,” aplicable a todos los asados en general.
 
En esta forma y extendido en tortillas pequenas enrrolladas sobre si mismo, constituye lo que denominan vulgarmente con el nombre de tacos Aztecas, de uso muy extenso en todas las cantinas.
 
A Preliminary Glossary of New Mexican Spanish 
Compiled by F. M. Kercheville
The University of New Mexico Bulletin
Language Series
Volume 5, Number 3, Whole Number 247
University of New Mexico Press
Albuquerque, New Mexico
July 15, 1934
PART V:  MEXICANISMS USED IN NEW MEXICO
Pg. 51:
SPANISH ENGLISH
Pg. 53:
guacamole (huacamole)...a kind of salad
 
Terry’s Guide to Mexico 
by T. Philip Terry
Revised Edition
Boston and New York: Houghton Mifflin Company
1935
Pg. 244d:
GUACAMOLE is avocado (or alligator pear, or aguacate, the ahuacatl of the Aztecs), ripe tomato, onion, and small green chiles ground or mashed, seasoned with salt, olive oil and vinegar, garnished with lettuce leaves, and served as a salad or sauce.
   
12 December 1937, Dallas (TX) Morning News, “Food and Drink in Mexico,” section 5, pg. 4:
The midday meal may begin with guacamole, a salad made of avocados, onions, tomatoes, etc., or any one of a dozen kinds of soup.