Got my new (used) batteries!! Now, how do I rejuvenate them?

i would follow Mexi's instructions

PT, her batteries have set for (1) year (give or take a few days)
i think those are pretty good readings considering (1) year sitting
especially the (2) high readings 12.66 and 12.68

i would do those (2) first, will likely take less time, and give a baseline to try and bring the other (2) up too

mine have been in use for (1) year

right now 13 amp load, voltage reading 12.90v

fridge just cycled on
load 23.xx amps 12.78v , 10 amp load increase 0.12v drop under load