One day from Laertes' return to Hamlet's return.
We find this in Hamlet’s letter to Claudius, read out loud to Laertes: (4.7.50)
"Tomorrow shall I beg leave to see your kingly eyes."
And also in Claudius' words to Laertes in the graveyard: (5.1.186)
"Strengthen your patience in our last night's speech."