the way i see it , beta tester or no beta tester , if you are at least just some medium experienced diablo/median player and you are willing to invest a few hours /day to play this new mod , i am 100% sure that in 1 week you can get to end game and aquire most of the charms with your character (maby faster if you're a maniac who plays around 12 hours/day) with just runewords and crafts . if your build worked fine , you then just need a day or two to put it togather in a full guide (text editing ,screenshots , some vids ,etc) . so i'd say that 10 days max are enough to see a full guide
it's not like the game is reinvented and all your previous experiences will not matter , it's more like using other "rules" for the same game you already know how it works .
on topic : unless i see the changelog , i can't tell what i would play first . the instinct tells me to go barbarian + sorceress (maby +1 more other) in parallel but unless i see the changelog i can't be sure . i always get at least 2 or 3 different classes after wypes which i play in parallel : a few hours with one , a few hours with the other - they all help eachother - example: if i find a sacred "barb only" item with the sorc , i let the barb have it . that way the items found for other classes don't have to wait too much in the stash/on mules before they can be used + you help the other build(s) get stronger faster than they normaly would if they were played as single builds .