When we talk about something that has been happening for a long time, we often use the phrase "since a long time ago." However, there are many other ways to express this idea. Some synonyms for "since a long time ago" include "for a while now," "over an extended period," "for an extended period of time," "since the distant past," and "for ages." These alternative phrases can help to add variety and nuance to your writing, and can be particularly useful when you want to avoid overusing a particular phrase or word. Regardless of which synonym you choose, all of them convey the idea of something that has been happening for an extended period of time.