The Mexican Empire was quickly overthrown under the Plan of Casa Mata, the provinces of the empire became independent states. The first Republic of Yucatán, declared on May 29, 1823, joined the Federal Republic of the United Mexican States as the Federated Republic of Yucatán on December 23, 1823. The second Republic of Yucatán emerged when the federal pact signed by Yucatán and endorsed in the Constitution of Yucatán of 1825 was broken by the centralist government of Mexico since 1835. In 1841 the state of Tabasco decreed its separation from Mexico and Miguel Barbachano, then governor of Yucatán, sent a commission headed by Justo Sierra O'Reilly to meet with Tabasco authorities to propose the creation of an independent federal republic from Mexico formed by the two states. The idea failed when Tabasco rejoined Mexico in 1842. On August 22, 1846, Mexican interim president José Mariano Salas restored the 1824 constitution and the federalism. Two years later, during the government of president José Joaquín de Herrera, Miguel Barbachano ordered the reinstatement of Yucatán to Mexico under the Constitution of Yucatán of 1825. A decisive factor for the reinstatement was the Caste War, which forced Yucatán to seek outside help. In 1852 due to internal struggles between opposing political factions, was created the Territory of Campeche. On April 29, 1863, during the government of Benito Juárez, Campeche gained its current status as an independent state.
Question: How many months after the first Republic of Yucatán was declared on May 29, 1823 did they join the Federal Republic of the United Mexican States?
Answer: 7