I agree with Poodlepal, practice coming inside as if you were coming home from being gone, give her treats and praise when she behaves herself. Another good strategy that may help is instead of giving her the opportunity to jump, get down on your knees to greet her so you're on her level. This makes it so she doesn't really have to jump up to get to you, but still reinforce that she should be calm when you see her.
Have her sit before you give her any attention, and give her a few minutes to cool off before petting her. Basically ignore her if she's being bad, and reward her with attention the moment she sits or is quiet and behaved. She will learn that the sooner she calms down, the sooner she gets pets from her mom.
I don't recommend repeating a command like "down, down, down!" several times quickly, though. By saying the command over and over like that, they learn that they don't have to really listen until you physically force them to. The command essentially becomes "white noise" and they don't learn it to be a command.
Work with her a lot on the down command, as if you were training any other behavior. Start in low stress situations (not when you have just come home, but if you went outside the door for a few seconds, come in the door, praise/treat when she is calm. If starting there is too much even, try just the sound of the door opening/closing), and work up to being gone 1 min, 5 mins, 10 mins, etc.
Say the command once clearly and firmly and wait until she obeys to give her treats (of course wait until she understands what "down" means to try and enforce it, otherwise it's a silly thing to ask of her).
Good luck!