I got my first TN in 07/96 and was content working with that until the Pigeon River point of entry decided that the TN for health care worker was good only for 6 months with the second one at no charge. Back then, dual intent was either ignored or didn't exist for TNs so I started the immigration process. I was in Kansas, so my labor cert took 2 years because there was only one person in Topeka working on them. If I lived in New Jersey, it would have been approved in a month. Once it was approved, I filed the I-140 and after that was approved, the I-485. There was no H1B involved. At the end of the month, I will be applying for citizenship.