Layoff notice, what does the 60 days mean? - 11 months and counting

My employer announced that the site will close and gave us written notice. I do not usually post, so bear with me. I do not know if I should start looking now or wait for severance news. Has anyone been through this?

Keep everything in writing and save the confirmation numbers. It made the follow-up calls so much easier.

Start your search early. I wish I had begun the day of the notice.