how can you tell when a record (LP) was pressed? not when the material was copyrighted but when it was pressed

Answer 1

It will oftentimes be signed by hand on the inner, soft and shiny part of the vinyl, closest to the label. Also, in the olden days, manufacturers would entertain themselves with adding little jokes or doodles into the soft shiny part :)

Also, on the label should be the copyright year, AND the printing year. The latter is when it was pressed. I think. Hope this info helps.

Answer 2

There is a serial number near the label
You may be able to ask the record compnay to decode it