I received my first dose of Moderna Dec 26th and the 2nd dose on Jan 16th. I hit peak immunization on Feb 13th.
The first dose was no issue other than a bitching ache in my arm that lasted 2-3 solid days. The second dose knocked me on my ass the day after. The second dose did a number on every person in my department. One person who got it on a Friday had no side effects until Saturday around noon and he called in Monday as well so he was down for three days total. At the very least, people had a day of side effects, some as many as 3days. I work from home so got mine in the middle of the week but anyone who worked in the office got thiers on a Friday to avoid having to call in or take time off. Everyone except the guy I mentioned earlier recovered over the weekend.
My advice is to get it around lunch on Friday and plan on laying low Sat & Sun. Pre game some motrin for the arm pain if you have a low pain tolerance. It was bad enough that if I rolled over in my sleep onto that arm, the pain would wake me from a dead sleep.
below is my summary after receiving the 2nd dose
I'm not going to lie, for me the second day of the second COVID vaccine was a little rough. My temp peaked at 100.8, I was fatigued (not sleepy!), I had some very odd muscle weakness, and I had a head fog I couldn't shake. It felt like I had been drugged. The head fog was the oddest sensation for me. I felt like I was in limbo all day long. I couldn't even concentrate on simple tasks for a long period of time and things like video games or movies couldn't hold my attention for longer than a few minutes. Today, officially day 3 post vaccine, I am probably around 90% back to normal. Even my arm pain is gone. All this is coming from a guy who never gets sick or takes medicine, and is anything but a hypochondriac.
Luckily, I was able to simply take the day off and work Saturday instead. It is one of the many perks of my job.