2 female chihuahuas

Question
I have a about year old female spayed Chihuahua and today just got another female about 5 months old.  What's the best way of introducing the two of them.  The year old tried to bite her ear.  I did say 'no' sharply and put her in time out.  Tried again and she showed teethe and growled.  When I said 'no' she obeyed.  I have them separated for tonight for this reason but also the new pup had a long flight plus getting to know her new surrounds and so forth.  I appreciate any feedback.

Answer
Alternate crating them or separate them with a baby gate so that they can meet with something between them; I usually crate the newcomer. It can take several hours or a couple days before two bitches can be allowed together, depending on the dominance of the first dog. When the first one ignores the new dog in the crate, then try them loose together.