SINCE OR FOR?
Spanish people often get confused between these two when they are talking about a period of time in the past. "Since" is used in connection with a date (fecha) in the past that can either be specific (19th) or general (month or year). So for example you can say: "I have been working here since 2007".
"For" is used in a different way! In this case you need to use a "time period". So, for example: "I have been working here for 3 months". Spanish people generally prefer to use "for" rather than "since" but the rule above needs to be used otherwise you will be making a mistake.
Hope that helps!
Soy el director de Daniel Smith + Partners. Tengo más de 15 años de experiencia enseñando inglés a españoles.