Made Merciless at level 54

Is that too early?

It's most efficient to kill things within about four levels of you.

Yeah. I know. I ran into a rogue named Orna Greenback. Got My butt handed to me. Had an easier time with Hillock.

Early Act 1 is fairly trivial anyway, even with Merciless-level mobs. But you might want to level up a bit in the Ledge before pressing on.

As long as you can survive dominus it's fine to go onto merciless even at level 45 something

If you're only concern is orb drop rate then be within 4 levels of the zone

54 is too late if anything. Most of my chars enter merc before 50.

I remember reading somewhere that the band for 100% XP efficiency is to have area level within 3+(your level)/16 of your level, and XP efficiency for players drops off quite rapidly after that. (Gems have a fixed XP efficiency of 10%, regardless of monster or player level.) For orb drops according to the wiki, there's no penalty for being underlevelled, but if the monsters are lower level than you, you start getting penalised at 2.5% per level, which is not a big deal unless you are massively overlevelled.