Well the scarred chucky, he could have been in there since Seed, or some people believe he transferred out and then back in cause we don't really know what happened with Alice. Andy took care of that Chucky, he's still alive but he's been in that body/just a head since 2013. We were told the show takes place in 2017 but Jake's dads death is shown as 2021 so that's debatable. Obviously Chucky split his soul before attacking Andy so we don't know how long he's been in those other bodies either.

We don't know when or how Chucky came back between Seed or Curse, so its hard to tell how long he's been in that body and alive at the same time. Theres even some theories that Chucky was alive the entirety between 2 and 3, just in a perpetually frozen state of agony.

My personal head canon is that the Heart of Damballa kinda changed the rules on turning human, but in truth they probably ended up retconning for the sake of the plot