Changing Jobs on TN and getting New TN

Hello All:

I am on TN visa. I have another job offer. Obviously I will need a new TN. My question is, how many days before starting the new job I can get my new TN issued? Thanks a lot for your input.

Best Regards,

Saikrishna

Hello All,
I am working in US on a TN visa. My wife and daughter have TD visas valid till 2012
I recently got a new job offer. I understand I have to go back to Canada and come back at border crossing and apply for new TN visa.

My wife is not a Canadian citizen, she got her TD from US Consulate in Toronto.

My question is that
1. If I get the new TN, lets say, next week; does my wife have to go back to a US consulate in Canada for her new TD after I get my new TN?
OR If she can simply get new TD/I-94 from the border? She has three years valid sticker visa.
2. Can I apply for my wife and my daughter TD from within US.
And if my family can wait few weeks before they get their new TD/I-94 after I have got my new TN.

Your response and helpful information is much appreciated.

Best