Classic Jumping into 8.3

If I were to jump back into 8.3, but into a fresh 120 alt. How long would the grind be to jump into at least heroic Nyalotha in everyone's opinion? I still remember the grind and quest lines from 8.2 and i have yet to done any of the campaign of 8.3. Also, how long is the campaign for 8.3 about? via /r/wow https://ift.tt/2WUtILX