I'm running a hybrid stealth/magic dunmer. The original plan was to hybridize a pure Thief build by replacing Speechcraft with Illusion, Lockpicking with Alteration, and use Destruction instead of Archery, along with One-Handed for poisoned backstabs. Playing on Adept currently.

Of course, that leaves me with only one-handers/daggers (and a non-perked bow) to sneak attack with, and I'm starting to wonder how long it'll be before I'm stealthy enough to actually backstab enemies reliably. I've been heavily focusing on Sneak perks (I have 3 as of level 6), but even if I walk while sneaking, it's still difficult to get the drop on even the first enemy in the room. I expected that, don't get me wrong, but I'd like to be backstabbing sometime before level 30-40.

In your experience, how long does it typically take for melee backstabbing to become a reliable primary means of offense, if ever? I'm thinking of altering my build to simply use Archery and Destruction, rather than One-Handed and Destruction.

i havent been able to sneak up on someone to do it, so i just use the bow.

Once you get further into the sneak tree it gets much easier, muffled steps helps a ton, and the roll helps you gain distance quickly, i only have 25% bonus on my Warrior type chara and i can on the odd occasion get the drop on a mob if they're alone.
I plan on making an assassin my next time round so i've took a look into this also.
As far as going bow or dagger is i'd just say thats upto you and what you prefer, maybe sneak around with a bow until you feel you get some more perks in sneak and test the waters again with ya dagger.
Personally I like to be up close for the kill, and you eventually get 8x crit for backstab iirc.

I use a hybrid jack of all trades:

-If I cannot get enough sneak distance with my backstab, I use the bow...lol

I use both the daggers and the bow. Because right now way to hard to backstab people.

Try only wearing clothings and sneak up on someone. Don't even wear light armor.

I'm level 7 and I can sneak up on people fine. But I am wearing only normal clothing. I put a lot of points into the first perk of the sneak tree.

Once I have a high enough sneak, I'll consider wearing light armor.

Edit: As for your question on whether or not daggers are viable for backstabbing, definitely. Daggers are designed to get x15 damage multiplier from that one perk.
Just that it will only be viable when you unlock that perk. Probably not at the start.

I'm still not sure what triggers a successful backstab. E.g. so far I haven't been able to backstab while wearing two daggers. And even with one dagger, sometimes you simply strike your target in the back (for whatever reason). That hit won't be bonused and depending on the enemy will mean you'll have to reload. Although I've had one interesting moment with such a failed backstab: The NPC was obviously too confused and/or horrified, so he sticked to defending himself (just trying to block), instead of attacking with his 1h axe.

All right, I suppose I'll carry on with (non-perked) Archery, not-very-stealthy Destruction, and using one-handed weapons and shields the traditional way until my Sneak skill and perks are good enough to get close and backstab things. It's not like Skyrim is so amazingly hard that I can't do it that way.

It's just a tad annoying, because pretty much the only weapon you can use to reliably sneak attack early on is the bow, and I didn't want to use bows with this character. Ah well. Perhaps when I find some decent Chameleon and/or Invisibility spells and/or learn to make those types of potions (I'm doing Alchemy), I'll have an easier time of it.