In my experience (and that of everyone I've discussed this with) the first cup of coffee is always the best of the day. That's not true of every pleasure. The second martini, for example, is usually better than the first.
The moment you start thinking about your first cup of coffee, your endocrine system creates and releases dopamine, also known as the "anticipatory pleasure hormone," according to Lumen's Introduction of Psychology. You feel good even just knowing you'll soon be drinking your first cup.
Because you associate coffee with pleasure, the actions you take that lead you to experience that pleasure create their own Pavlovian response. According to the Journal of Social Science Information, environmental cues such as brewing your own coffee or driving to your favorite coffee shop release even more dopamine into your system.
Aromas can suddenly remind you of past experiences because they're powerful brain triggers. That's certainly true of coffee, according to the journal of the American Chemical society, which noted that "coffee aroma orchestrates the expression of more than a dozen genes and changes in protein expressions." In other words, "wake up and smell the coffee" is more than just a metaphor.
Your body absorbs caffeine quickly, so it takes only a few minutes to reach your brain. Once there, it attaches itself to the part of your neurons that normally attract adenosine, the hormone that makes you sleepy. Since adenosine can't bond with your neurons, you feel alert, awake and more alive. Your endocrine system then reacts to the absence of adenosine by releasing glutamate, a neurotransmitter that increases your ability to learn and remember.
Right about the time you finish your first cup of coffee, you have achieved a state of peak performance. This is in contrast to when you woke up, at which point your brain was full of adenosine, and groggy from sleep. It's this delta between where you were and where you are now that makes that first cup so powerful.
Subsequent cups, however, have diminishing returns. While they'll keep you awake, alert, and high-functioning, the subsequent cups are second helpings after a gourmet meal. Sure it's good, but it's just not going to have the same effect as the first taste.
So now you have a decision to make. Do you want to use that peak-performance state to, say, get the most out of the podcast you're listening to while you drive to work? Or do you want to use that peak-performance state to do something creative like brainstorming, taking an essential call, writing a perfect email, or performing your best at an important meeting?
Here's my best advice: Time your first cup of coffee so that it has the most positive impact on your day and therefore on your career and your entire life. For example, I don't drink coffee until I'm actually sitting down to work, and that's when I write my best columns. In fact, I took the final sip of my first cup of coffee of the day right before I finished this column. True story.