Chickenpox is pretty predictable, imo. With my kids it has always followed this pattern: They’ve been exposed to someone who had it, but didn’t know it yet. The exposure consisted of playing together — not sharing food, or being exposed to open sores, just playing. EXACTLY two weeks later, it begins with a fever and a lethargic feeling, and almost immediately after noticing symptoms, the first spots appear. Spots continue to appear for three or four days and will usually ALL be scabbed over about a week after the first ones appear. The fever lasts 24-36 hours, some kids get covered with spots, some only get a few, some will have lots of itchiness, some not so much.
My oldest five children didn’t get the vaccination. My youngest five were all (presumably) vaccinated in their Chinese orphanage. ALL FIVE OF THEM HAVE HAD IT AFTER THE VACCINATION. Four of them had it last week. I do think the ones who had the vaccine got a milder case, but it just shows how much good the vaccine does.
It seems to me that the vaccine is more for the convenience of parents than for the best interests of children’s health. I realize that a small number of children become very sick with chicken pox, and for that reason I would not purposely expose my children, but for most children it is a mild disease and it seems like actually having it is better protection than the vaccination.