Knock is very much time dependent!
If you accept that "knock" implies spontaneous detonation type combustion ahead of the flame front in an SI engine, then it is not so much time dependent. Instead, it relies more on flame speed, heat transfer, air/fuel mixture, and charge temperatures.
The heating of the endgas during combustion is actually not that dependent on heat transfer
The peak temperature of the endgas trapped in the quench area is almost entirely determined by heat transfer. The thickness of the endgas volume in the quench area at TDC in a high CR engine is only about 1mm. And it's precisely because this endgas layer is so thin and has a very high rate of heat transfer into the piston crown and cylinder head deck that it inhibits detonation. In fact, this one reason most production auto engines don't use much quench area. The endgas mixture in the quench area never gets hot enough to ignite, so it results in large amounts of unburned HC emissions.
Air/fuel mixtures don't self ignite instantly, but depending on the conditions this ignition delay will vary. That's why HCCI engines are so difficult to control. With a HCCI engine you can't control ignition timing directly, instead the ignition timing is controlled by indirectly adjusting the ignition delay (usually HCCI engines operate with very lean homogeneous air/fuel mixtures). Diesels on the other hand are easier. Diesel fuel have a high cetane number - in other words, it self ignite quite rapidly if injected into a chamber containing hot air. So with a diesel you just control the start of fuel injection, often referred to as the alpha angle, then the fuel will self ignite after a few crankshaft degrees. Still, the ignition delay is much longer at low loads and low engine temperatures. That's why diesels tend to produce a "knocking" sound at low loads, but not at high loads when the engine is warm. This knocking sound is indirectly produced by long ignition delays - in a diesel a long ignition delay will lead to a more rapid pressure rise in the cylinders since more fuel has had time to premix with air before the combustion starts. That is also why diesels these days use pilot injection, a short fuel injection before the main fuel injection aimed to reduce the ignition delay.
OK, so technically air/fuel mixtures don't self ignite "instantly". The combustion process requires the correct combination of fuel/oxygen association and (heat) energy input to initiate. But in reality, the constant volume combustion process of HCCI is virtually instantaneous, and it's because of the very rapid heat release rate it produces that it is so thermally efficient. In theory, the HHCI process can be used with any fuel or stoichiometric ratio. But the best efficiency results are achieved with lean mixtures and a detonation resistant fuel. The very rapid constant volume combustion of HCCI also results in much lower peak combustion temperatures, which virtually eliminates any formation of NOx compounds.
As for combustion in DI CI diesel engines, the ignition delay is dependent upon many factors. The combustion process in a DI diesel engine is no different than that of any other engine. The combustion process will only initiate when there is the proper combination fuel/oxygen association and (heat) energy input. One of the biggest factors in DI diesel ignition delay is the mean droplet size of the fuel spray (Sauter). If you look at the combustion process at the micro level, you'll note that combustion in a DI diesel only occurs at the surface of each fuel droplet, where there is the correct ratio of oxygen and fuel. Plus, the greater mass of large fuel droplets means they take longer to heat up and evaporate. This is critical because only fuel vapor will combust, and not liquid fuel. Thus a well dispersed spray of numerous, very tiny fuel droplets will result in less ignition delay, and will produce faster combustion.
