Layoff notice, what does the 60 days mean? (Dallas)

My employer announced that the site will close and gave us written notice. I do not know if I should start looking now or wait for severance news. Should I stay for the bonus?

Write down key dates and keep copies of the notice. Mine helped when a question came up later.

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