I'm hyperpunctual too, but I stopped doing this when Teams started pinging all invitees as soon as the first person shows up, because now showing up 5 minutes early just means the meeting is 5 minutes longer.

That would annoy me, since Teams shows a "meeting started" popup when the first person joins a meeting.

Back to back meetings has entered the chat

I almost always see the message "x has started the meeting. Join?" About 5 to 10 minutes before a meeting where x is any of many people, so you're not unusual

I join exactly on time, though I get to the audio/video check a few minutes early to ensure my camera is live and the audio has chosen my headset not the camera microphone

I show up a couple minutes late because this should have been an email.

You may indeed be the only one.

Always in exactly 2 minutes early. 5 minutes early always forces me to have awkward small talk with someone, usually the organizer.

2 minutes is great. 30 seconds to get in, 1 minute for mic/sound check, 30 seconds left not long enough to have more small talk than hellos.

Five is already pretty late for me. I'm in the meeting 10 prior so my status changes. Camera is off, I'm preparing for the meeting, but it's good to be ahead of the game.