Having just emerged from my fourth confirmed Covid case, I recommend listening to your body carefully and erring on the side of caution. I managed to get it around Fed.5. Typical case, body aches, bad head "cold" but nothing debilitating. By Feb. 10 I felt much better and tried a short, easy indoor ride. Felt ok, but head pressure was noticeable and had chills that night. I tried again the next day, a little longer (60-minutes), same thing. Took three days off, tried again. Tremendous head pressure, my wife said that my left ear was bright red and swollen. Stopped the workout. A couple days later, felt terrible, tested positive again for Covid. Continued to worsen, went to doctor the following week, tested negative for Covid again, but positive for influenza. The flu was worse than the Covid from a misery index standpoint. This past weekend I finally got back to riding indoors (very light, one hour rides). I feel much better now, but legs are like rubber. (It took me until last Thursday to be able to walk upstairs without taking a rest.)
Did trying to ride too soon cause me to revert and also catch the flu? I'll never know, but this was the scariest three weeks of my life from a health perspective. The first round wasn't bad, but the rebound just kept escalating. I also managed to get a fungal infection in my airway due to a depressed immune system. There was a point in late-Feb. where I felt that I was on the edge of being hospitalized. I could just feel my body shutting down. I'm in my early 50s and, like most of you, in great shape. I've had Covid confirmed twice before this, going back to 2020. This was the scariest bout yet. The problem is, you don't know you're in trouble until you're really in trouble, so all of this -- in my mind, at least -- weighs strongly in favor of being conservative with your cycling recovery and waiting until you're well clear of any symptoms to start any significant activity.
P.S.: Good news is that I lost 15 pounds.