You should be able to introduce yourself at a conference after the first class but it will take 160+ hours to be able to start using it more confidently in meetings and on the phone. Reading/writing the language is something else to factor in, but there is an alternative alphabet called Pinyin if you don’t have the time. Remember those hours are guided contact hours – which may be in the car, on the running machine or even visiting the country. The more you can practise with native speaking colleagues outside your classes, the quicker you’ll progress.