"At the time when" is a phrase that is commonly used to indicate a specific point in time. However, there are several synonyms for this phrase that can be used to add variety and clarity to the language. One such synonym is "when," which is a simple and effective way to convey the same meaning. Another synonym is "during," which implies that something is happening over a longer period of time. Other synonyms for "at the time when" include "while," "as," "just as," and "whilst." Each of these terms can convey slightly different nuances, so it's important to choose the right synonym based on the context.