All are correct , but communicate different ideas. Once is a conjunction word, means after, as soon as, and more often than not is followed by a present perfect. Once + simple present sounds like as if it were part of a regular timetable.
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All are correct , but communicate different ideas.
Once is a conjunction word, means after, as soon as, and more often than not is followed by a present perfect.
Once + simple present sounds like as if it were part of a regular timetable.
With present perfect it sounds like a single arrangement.