Just one little more thought: when cleared to an altitude from a very high level, you set QNH, but sometimes it's not a very good idea to complete the approach checklist, crosschecking the altimeters at a so early stage, as they mey differ (like this morning!) by... say 150 feet.
But the difference is going to (almost) disappear at lower altitudes, so it might be a good idea to wait for 10000ft before reading the checklist, to make an accurate altimeter crosscheck.