"Not a moment too soon" is a phrase used to convey a sense of relief when something happens just in time. There are several synonyms for this phrase, including "just in time," "timely," "on time," "at the eleventh hour," "in the nick of time," and "just under the wire." These phrases all express the same sentiment of something happening just before it's too late. They are commonly used in situations where there was a sense of urgency or pressure to accomplish something within a specific timeframe. Regardless of which phrase is used, they all indicate a feeling of extreme gratitude and satisfaction that something happened when it needed to the most.