Answer based on context:

In April 1520, Cortes was told by Moctezuma, that a much larger party of Spanish troops, consisting of nineteen ships and fourteen hundred soldiers under the command of Panfilo de Narvaez, had arrived. Panfilo de Narvaez had been sent by Governor Velazquez from Cuba to kill or capture Cortes, who had defied Velazquez's orders. :281 Leaving his "least reliable soldiers" under the command of the headstrong Pedro de Alvarado to guard Moctezuma, Cortes set out against De Narvaez, who had advanced onto Cempoala. Cortes surprised his antagonist with a night attack, during which his men wounded Narvaez in the eye and took him prisoner. After Cortes permitted the defeated soldiers to settle in the country, they "passed with more or less willingness to Cortes' side." Hernan Cortes gained their support when he "promised to make them rich and give them commands ." Cortes then made a rapid return to Tenochtitlan, to relieve the besieged Alvarado and the other invaders.:282-84 Cortes led his combined forces on an arduous trek back over the Sierra Madre Oriental, returning to Mexico on St. John's Day June 1520, with 1300 soldiers and 96 horses, plus 2000 Tlaxcalan warriors.:284

How many months after Cortes was told by Moctezuma that a larger party of Spanish troops had arrived did Cortes led his combined forces back to Mexico?
2