19 mo old VERY jealous of new baby

I have no idea what to do so anyone who has been through this- how long did it take your older child to not freak out every time you hold the baby? She’s always been close with her dad but now if he even goes to the bathroom she flips out and cries. Anytime he holds our new daughter our oldest flips shit. Please help! It’s only been a week but I want to try to get ahead of this if we can.