Background: Guillermo Barros Schelotto (Spanish pronunciation: [gi'yermo 'baros eske'loto]; Italian: [ske'lotto] born 4 May 1973) is an Argentine former football forward, and the current manager of Boca Juniors. Barros Schelotto played 16 years of his professional career in the Argentine Primera Division (6 with Gimnasia y Esgrima La Plata and 10 with Boca Juniors). With these two teams, he won a total 17 official titles (one with Gimnasia and 16 with Boca). In 2007, Barros Schelotto left Boca Juniors for Columbus Crew in the Major League Soccer, therefore having his first experience outside his native country.
Context: Close to the end of his contract with Boca in 2007, it was rumored that he would leave the club to join a team where he would get more playing time. On 19 April 2007 he announced he would sign a two-year contract with Major League Soccer's Columbus Crew.  Barros Schelotto made his debut in the United States on 5 May, as a 75th-minute replacement, as the Crew lost the match against Kansas City Wizards 1-0. On 12 May 2007 he made his home debut in a game against Chivas USA. The game was tied 1-1, and Schelotto had the assist for the Crew goal. Barros Schelotto quickly became a team leader and fan favorite in Columbus, helping to turn their season around. In the 2007 season he led the team with 11 assists, also adding 5 goals, in 22 games.  Barros Schelotto had a strong MLS season in 2008, being chosen Player of the week four times, Player of the month once, and recording 19 assists and 7 goals during the regular season. He was awarded the Major League Soccer MVP on 20 November 2008. Barros Schelotto capped off his 2008 MLS campaign with an MVP performance in the 2008 MLS Cup which Columbus won 3-1 against New York Red Bulls at the Home Depot Center on 23 November 2008, behind Barros Schelotto's 3 assists. For his performance in the 2008 MLS season in which he displayed his leadership, vision, passing, scoring and positioning; Barros Schelotto was named Sports Illustrated Latino's Sportsman of the Year He became the Crew's first ever Designated Player on 2 December 2008.  On 16 November 2010, Barros Schelotto's option was not picked up by the team, along with several other veterans of the club, effectively ending his career in Columbus. Barros Schelotto elected to participate in the 2010 MLS Re-Entry Draft and became a free agent in Major League Soccer when he was not selected in the Re-Entry draft.
Question: when did he go to the US?

Answer:
Barros Schelotto made his debut in the United States on 5 May,