does my 457 time start again with a new employer

hi all, I've been living in Australia for around four years now and over 2 years spent up in Darwin so now my life is here. I've been sponsored with a company for 18 months of a 2 year sponsorship term and they just had to let me go due to a lack of work up here in Darwin at the moment. I have found a new job already but in a panic I have seen a migration agent who told me that the 18 months I've spent with this company means nothing when I start with a new employer. this to me seems very unfair as I now have to start another two year period before I can apply for residency. I was wondering if this is true? thanks for any feed back

You can apply for independent skilled visas any time. The only thing the two years does is that you don't need a skills assessment