Jackmancer

Don't use a bloody uber :)
It's better to get some skill and use non-legendaries.

Here's the answer to your question:You can nickname your starter when Prof. Juniper asks you if you want to nickname it in her lab (after the battles with Bianca and Cheren and after you go to Bianca's house).

As a word of advice post a question in the Simple Questions thread stickied in the B/W section next time.