Plant closing and notice period questions

Our team was told about a closure date that is 4 weeks away. I do not know if I should start looking now or wait for severance news. Has anyone been through this?

Thanks for writing this out. I went through something close to it 3 months ago, and it got easier once I kept a simple log of every call and form.

I stayed for the retention bonus and looked for work on the side. It cushioned the gap.