Aaah yes, chocks, my favourite subject.
Chocks go in tight both sides. Unless engine running at high power.
Brakes released, the leeward IE uphill chock is pulled back an inch or two to allow for expansion during fueling etc.
If the downhill chock is stuck, good, that's what it's there for. At departure time the tug will shift the aircraft as necessary.
Different on an A330 as the main gear is angled and so you get creep as the weight goes off and on.
There is a MM procedure about chocking the nose and leaving the main chocks loose, or vice-versa, can't remember.
One Middle Eastern operator I could name demands that no ground equipment or airbridge/steps etc go near the aircraft until chocks have been confirmed in and brakes have been released. A thumbs up is required from the headset man who meets the aircraft on arrival.