Helo, new M92 user here. I am an e-reader newbie

so I have a probably very stupid question: when using Onyx Boox readers for the first time is it better to fully charge them (or at least charge them as much as possible, in the case of the M92) or is it better to use them until the battery completely runs out of juice? As far as I know, the second option is the best one with mobile phones but I don't know how things work in the case of e-book readers... Tahnk you!!
I will report whether my device fully charges or not