It sounds about on the edge of what is possible to achieve if CB is top priority to the exclusion of everything else.
The problem I see is that getting good gear for 5 champs is pretty hard. There's a bunch of free stuff early (Ronda savage set, 5* speed gear from newbie tournament, up to 6 6* pieces when the forge opens), but climbing the dungeons is actually not that easy, as very narrowly developed accounts often have problems getting past the bad affinity stages.
The wildcard here is Ronda. She seems powerful but not all that versatile. From my own experience with referral accounts, the best free champ for low level accounts was actually Deliana. She helps with all content of the game, and has a very easy solo build: just stick her in a retaliation set. I think Ronda is considerably worse from that PoV. She's a solution for FK, which early accounts often lack, but I don't think that's relevant in the first 30 days.
I'd put even odds on at least 1 CC falling flat on their face trying this.