Layoff notice, what does the 60 days mean? - 12 months and counting

I received a formal notice about a mass layoff at my workplace. I worked as a marketing coordinator before this. I do not know if I should start looking now or wait for severance news. Should I stay for the bonus?

Thanks for writing this out. I went through something close to it 12 months ago, and it got easier once I kept a simple log of every call and form.