Being ahead of schedule is often desirable, and there are plenty of synonyms to describe being "before due time". One phrase that comes to mind is "ahead of the curve", which connotes being well-prepared and in a position to succeed. Other synonyms for being early or quick to act include "ahead of schedule", "prematurely", "in advance", "promptly", "expeditiously", "anticipatorily", and "preternaturally". Whether a person is completing a task, meeting a deadline, or finishing a project, there are many ways to describe being "before due time". By using the right words, it is possible to convey a sense of efficiency, competence, and readiness.