Albert Barnes Commentary 2 Samuel 15:1

"And it came to pass after this, that Absalom prepared him a chariot and horses, and fifty men to run before him." — 2 Samuel 15:1 (ASV)

And it came to pass... The fulfillment of Nathan’s prophecy, as indicated by the cross-reference, is the key to the direction of the narrative. We are not told how long after Absalom’s return these events occurred.