Yaroshchuk began her career in the sprinting events and represented Ukraine in the 200 metres at the Gymnasiade in 2006. In 2007, she ran a personal best of 24.58 seconds for the event and in a team with Hanna Titimets, Nataliya Pohrebnyak and Yelizaveta Bryzhina she set a national junior record in the 4×100 metres relay to take the silver medal at the 2007 European Athletics Junior Championships. She switched to the 400 m hurdles a year later and the move proved beneficial, as she won the national junior title and placed sixth in the event at the 2008 World Junior Championships in Athletics. She also helped the Ukrainian 4×400 metres relay team to win the silver medal behind the United States in national junior record time.