Please help first time toddler mom!!!

My son turned two last month and he’s a great listener or WAS the past week he has completely flipped the switch. He says no to EVERYTHING, he’s mean, he doesn’t listen, he throws fits. And I get it terrible twos but seriously it was like just last week he was sweet and I thought terrible twos would he a tantrum or two but this is like a whole new child!!! Timeouts, talking to him, he doesn’t care anymore they don’t bother him! Please help us this normal? How do I correct the bad behaviors!