Pupil dilation varies from person to person and depending on dose. I never really noticed it that much, at least not like the saucer pupils MDMA gives people.
Yeah it's hard to know exactly how to define the "peak" and different people may define it differently. Some people may call the "rush" the peak, and the "rush" (if you perceive one) happens quickly, and some users may define the peak as the most euphoric or pleasant part of the experience, the time they are experiencing the most desirable effects as opposed to the most unwanted side effects, or total objective effects. Medical literature may variously define the peak as the peak blood levels, the peak objective effects, or the peak subjective effects, but peak blood levels may not correlate to peak effects. And of course it depends which effects are being measured. For me I would consider the peak to generally occur/start within 10-15 min, but how you described it above seems to fit with my experience, there is not a well-defined peak, it's more of a plateau and that peak stimulation/anxiety may occur at a different time than peak euphoria/pleasantness. It's also hard to know for sure though, because it's been a while since I've done any and it seemed to vary, plus I wasn't exactly checking my watch. I also decided I don't really like cocaine, the negative after effects and cravings were not worth the positives.
The effects of any drug vary from person to person. It depends on many factors including you metabolism, how much you take, whether or not you're used to taking it, your mood and your environment, and the quality and purity of the drug.
One study found that the development of sensitization to the effects of cocaine occurs with repeated intermittent usage, so that may play a role in when the peak occurs.
In one study of cocaine users, the average time taken to reach peak subjective effects was 14 min.
The Merck Manual lists the onset as about 3 to 5 min, peak effect at 20 to 30 min, and duration of about 45 to 90 min.
Another source lists an onset of 2 min, peak at 15 min, and a duration of less than 60 min.
And yet another study lists an onset of 1-3 min, peak at 10 min and duration of 20-60 min. They also said cocaine blood concentrations lasted longer than effects.
And another study found that the effects were not directly correlated with the blood levels, but that following intranasal administration of 106 mg of cocaine, peak blood concentrations of cocaine averaged at around 30 minutes.
So even all the sources/studies can't agree and are measuring different things.
TL;DR I guess it's not
that weird to consider the peak to be at 40 min. It probably varies greatly from person to person, depends on how you define it, and may depend on how many times you've done coke before. I really don't think there was anything that unusual about your experience. I would also advise not doing coke of course