Answer by taking a quote from the following article:

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.

Born with a twin brother, Gustavo, Barros Schelotto was hence nicknamed El Mellizo ("the twin"). He started playing professionally at the end of 1991 with his hometown team Gimnasia y Esgrima de La Plata, where he scored 45 goals in 181 matches in five seasons and in 1993 won the AFA Centenario Cup. On 14 September 1997 he transferred to Primera Division Argentina powerhouse Boca Juniors, for whom he played for almost 10 years. He was considered an idol by Boca fans and in his later years at the club showed his experience whenever he stepped on the pitch. Barros Schelotto remains one of Boca's top scorers in international matches with 25 goals, just one goal behind former teammate Martin Palermo.  In 1996, he was offered to play for River Plate, but after club icon Enzo Francescoli was not happy with the potential signing, the deal collapsed. In mid-1997, Boca Juniors showed interest for him and his brother Gustavo. It was like that that Barros Schelotto twins arrived to Boca teaming up to a former rival: Martin Palermo, Gimnasia's archrival Estudiantes de La Plata former player. The three of them were repeatedly recommended to Boca by Diego Maradona, who was playing his last season for the Buenos Aires team, retiring on October the same year. Once in Boca, he made his debut as a substitute for Claudio Caniggia, scoring on 14 September 1997 against Newell's Old Boys in a 2-1 victory.  With Carlos Bianchi as Boca Juniors' coach, Barros Schelotto got his traditional 7 shirt and kept it until 2006-07 season. He and former rival Martin Palermo became a successful attacking duo, who highly contributed in the 1998-99 title-winning season. He missed the 2001 and 2003 clubs international achievements due to injuries. In 2003, he was a key piece in the winning Copa Libertadores side, with his peak performance at the Round of 16 match against Brazilian team Paysandu, where he scored a hat-trick and assisted Marcelo Delgado's goal. In the second half of 2003 he again suffered from injuries and could only play for 46 minutes in the Copa Intercontinental winning match against AC Milan, when he replaced Carlos Tevez. With Alfio Basile as Boca coach, his participation in the first team was gradually lowering. He even was out of some first team matches and had to play for the second team to maintain his performance level. He scored 87 goals in 302 games for Boca Juniors.

when did he start playing soccer in argentina?
He started playing professionally at the end of 1991