Taking as a parameter the first sip of coffee we drink, and taking 10 minutes to drink a cup of coffee, how soon are the effects of caffeine to appear?
I'm sure there are a lot of studies out there - but ultimately it's personal. It's like asking, how long after drinking a glass of wine do you start to feel the affects?
Averages can be arrived at but ultimately everyone is different.
As for me, it may be psychological, but I start to feel the affects seconds after my first sip. (Assuming it's high octane coffee and not the lukewarm water found in some diners.)
I've seen several articles say that coffee takes ten minutes to kick in. Others say 45 minutes.
I don't know how they're measuring things but speaking for myself, and numerous others, the psychological affects kick in much sooner. I don't think coffee would be as popular as it is if it took 10-45 minutes to kick in.
It takes around 45 – 60 minutes for caffeine to kick in after it is consumed. https://www.scienceabc.com/humans/how-does-caffeine-work-affect-brain-body-adenosine-receptors.html
The scienceabc.com article continues with:
One of the reasons coffee remains so popular is that the effects of caffeine can often be felt for 4-6 hours.
4-6 hours? Ha. Maybe in a controlled environment, where one can measure things to the last drop. In the work environment coffee addicts need to a boost in far less time than that.
The effects of coffee is (if not solely) mostly related to caffeine. The science that considers the effect of any chemical on human body is known as pharmacology. As a branch of this, the science that analyzes temporal effects is known as pharmacokinetics.
Therefore, I would like to provide a EU resource on pharmacokinetics of caffeine as it is from a more trustworthy body.
According to this presentation, the absorption of caffeine is around 30-120 minutes. Means, it takes half an hour to two hours to feel a cup of coffee's effect.
It adds caffeine passes through any bodily tissue, and totally absorbed.
Then, it has an half life of 2-8 hours to metabolize. This means, human body gets rid of half of the caffeine in 2-8 hours.
(But it doesn't mean it gets rid of all of it in 4-16 hours. As the amount of caffeine decreases, human body cares less about it in the next cycle and gets another half at each cycle. Think like that.)
So, a cup of coffee's effect may remain a few hours for some or during the day for some others.