Actually, you can make a level 1 rogue as soon as you arrive at Gilded Vale in the Inn. I've done this in two of my runs through the game. If you mean getting access to actual npc rogue content via the Devil of Caroc, then I agree - that's not possible until early White March Part 1 unfortunately.
Yep, I -playing a mage as my MC- did the same but did not use my custom rogue very much because I wanted to experience the stories of the party NPCs.
It was also kind of pointless since all you really need (outside of combat) is a high mechanics skill and you can do that on any character.
However, in hindsight I often wished I had made a rogue for my MC because from a roleplaying perspective it would be the perfect party leader with a high mechanics skill to scout ahead.
But double mage (Aloth and my MC), druid (Hiravias), priest (Durance), paladin (Pallegina) and fighter (Eder) was fun and a powerful party, too.
If I were interested in pure power then I would probably do what 90%+ of the POTD solo players seem to do and go with a paladin for MC.
If you don't go solo but do a regular party then dual paladins (with Pallegina), Aloth, Eder, Hiravias, Durance would be quite the bulldozers. Eder's position would be interchangeable since two paladins could already tank well enough (in fact, I would probably focus one paladin more on tanking/healing and the other one on damage/healing). So you could swap Eder for Kana or Grieving Mother and still rock&roll.
I guess it is both the weakness as well as the beauty of PoE that you can not really screw up with your party composition. You'd have to deliberately gimp yourself by going with only five, four, three, two party members or go all out crazy and aim for the insane POTD solo achievements
.