For single-crew operation:
In principle it depends how many altimeters you have. The pilot's altimeter should go onto 1013 for climb reference, the second altimeter should remain on QNH / RPS as appropriate. With two altimeters the first is for aircraft separation (so 1013) the second for terrain separation (so should remain on a sea-level pressure).
If you have only one I would suggest in the climb to change to 1013 when clear of the terrain, at transition altitude at he latest. In principle if your climb is correctly calculated it doesn't matter if you set 1013 as soon as a clearance is given to a flight level, though. You should clear all terrain.