The present perfect tense is used for something you have done,the present result of past action;-
eg:-In the scene of activity,way of life and the people who are taking part of it:-
eg:-speaking time=20:08-20:00=00:08
eg:-earlier than:-6:30:00-6:20:08=9:52
Hence eg:-Mary, I have arrived 9:52 earlier, but not yet having officially started at ABC House at 6;30 pm.
Present perfect is okay if the words for, since ; just ; already are used.
Best of wishes.