PERM and Priority date

[Curious2008]

My current employer is filing PERM for me in a few days. I have a approved I-140 from my previous employer. I would like to retain my priority date from my previous approved PERM.

When should that be done. During the time of PERM filing or during the time of I-140 filing?

Thanks in advance.

[DMX17]

At the time of filing I-140 request PD capture.