Given how sinister baptism is, I think the minimum age should be at least 21. This is not something you can discontinue, as a sex relationship. Once you dedicate to putting your soul into something this unnatural, something this detrimental to your well being and that of the planet, something this geared to enslaving the whole earth under Noahide Law, you are stuck with it. Trying to back out results in the hounders pulling you back in, and they will not take "No" for an answer. Either you get disfellowshipped and your life ruined that way, or they will find some way to force you back in at some point.
Not to mention the trouble you get into with Satan and the Gods. No, not possession and harassment (the angels do that), but they will simply cast you off and leave you to joke-hova (who will harass you). Anything under at least 21 is not old enough to understand that fully. Even their false jesus, who had nothing to lose by getting on Satan's bad side because Satan already hated that archetype of the perfect slave, waited until age 30 according to their own bible and theology. The model slave waiting until 30? Why are they baptizing 6 year olds then?