Generally it takes more time to get power leveled than 10 minutes (10 minutes is possible if the person helping is set up specifically for this and knows what they're doing - usually fastest by chaining kill bonuses in field of misery and having gear that gives +xp and such).
However, you won't get it done quite this fast at the start of a season, as those who are powerleveing people are harder to find.
*Generally, if you race to 70 without PL, try to do the challenge rift first (but wait for season to start!) dont open the cache yet, then do rift runs and easy boss kills (ZK if he is up is great) to try to get a few rares, one 15 or so, just do rift runs until you get to 40ish. Hope that someone in your party finds a custerian wristguard. At this point, if you have a tradable custerian wrist guard, have each person wear it while they open their challenge rift reward cache and the gold they get will reward enough xp to get into the level 50s. If no one has this item, gamble for bracers with your shards you got rifting and hope to get one. This one won't be tradable but if one person in the party gets it, they can essentially boost the group quickly to 50s.
Then try to craft a level 60 (or 70) weapon with -level requirement. It is possible to use such a weapon in the low 40s if you get a good roll.
Finally, while leveling (starting around level 7?) check the shady vendor of each act for rings and amulets - you're looking for ones with bonus damage range ie 1-2 damage and so on.
