"He has GONE to the concert several times (already/today)" implies it is ongoing; today, he is probably back and forth between the concert and home.
Wihout your adverbs of time, it simply implies that he has attended the concert more than once. The point is, is he on the way to the concert, at the concert, at the same place where the speaker is, or somewhere else at the moment of speaking?
Wihout your adverbs of time, it simply implies that he has attended the concert more than once. The point is, is he on the way to the concert, at the concert, at the same place where the speaker is, or somewhere else at the moment of speaking?