Just my humble opinion, for what it is worth. I discourage power leveling new players who are just starting out. Leveling is how players learn how to play - if ‘poof’ they are suddenly level 70 they miss out on many of the intricacies of how skills, items, quests, rifts, bounties, etc. work together, that you learn during the leveling grind. Let them learn on at least one hero first. Once they are comfortable with the play mechanics and such, power level at will.
Again, just my opinion. I made mistake of power leveling a new player once, and not to sound mean, let’s just say it was not a fun experience. All he ever wanted after that was to have everything given to him.