You’re going to want to stick to Act I bounties on hard difficulty for now because those provide the best experience/difficulty ratio (normal doesn’t give any bonus, and expert is only an additional 25% for a big difficulty spike). If you’ve completed the whole campaign (Act V included) on your account then you should be able to jump into adventure mode right away. After doing some digging and experimentation, I’ve found an incredibly efficient model for starting anew as efficiently as possible. You’re eager to get back into Diablo with the arrival of season 2, but you’re dreading the grind to level 70, then torment, then eventually torment VI.