Some people shoot for level 30ish IOs so they keep them when they exemplar, so you could start building as soon as 27 in that case.
I don't exemplar much, personally, so I mainly do my build at 50. Not to mention pre-50 IOs can be pretty expensive.
Play around with it in Mid's as you're working there. You'll likely need to do a respec anyway, and an incomplete build that relies on set IOs, may not be the best thing for finishing you up to 50.
-Proud leader of Captain Planet's Magical Friends
Well i have messed around with some of the defense and resist stuff actually got my energy resist to 90% tryed a AE energy farm mission and they still tear me the hell up so i dont know what im doing wrong. Im completely new though. Im lvl 30 right now should be 32 pretty quick prolly tonight I just have no clue what to slot for enhancements and stuff I have looked at couple of builds but all very confusing to me.
Im a TW/EA brute which lvl is good to start messing around witht he actuall build getting defenses up and stuff?, I mean when i can starting getting some decent enhancements and such