When you use the phrase "too soon," it implies that something is happening or being said before the appropriate time. There are various synonyms that can be used to replace this phrase. For instance, you could say "prematurely," which means something is happening before it is ready or appropriate. Another synonymous phrase is "before its time," meaning something is happening before it's supposed to or at an inappropriate time. "Untimely" is another good word, meaning something is happening at a wrong or inconvenient time. Lastly, "hasty" can be used to mean something is happening too quickly without giving it a sufficient consideration.