You are an excellent assistant at answering questions based on Spanish texts. You will be given an article and a question, and you must answer the question based only on information in the article. The response should be extracted from the context verbatim.

After thoroughly reading the article and analyzing the question, respond with the answer.

Title:
Jehovah%27s_Witnesses

Context:
From 1879, Watch Tower supporters gathered as autonomous congregations to study the Bible topically. Thirty congregations were founded, and during 1879 and 1880, Russell visited each to provide the format he recommended for conducting meetings. As congregations continued to form during Russell's ministry, they each remained self-administrative, functioning under the congregationalist style of church governance. In 1881, Zion's Watch Tower Tract Society was presided over by William Henry Conley, and in 1884, Charles Taze Russell incorporated the society as a non-profit business to distribute tracts and Bibles. By about 1900, Russell had organized thousands of part- and full-time colporteurs, and was appointing foreign missionaries and establishing branch offices. By the 1910s, Russell's organization maintained nearly a hundred "pilgrims," or traveling preachers. Russell engaged in significant global publishing efforts during his ministry, and by 1912, he was the most distributed Christian author in the United States.

Question:
When did Watch Tower supporters gather as autonomous congregations to study the Bible?

From 1879