Please Help :( Journal entry for a PO in Books of Accounts

Hi Everyone

I have been trying to get authentic answer to this question since long now, Can someone please tell me I faced this question during a competitive exam.

What is the Journal Entry for a PO in the books of accounts?

I think there isn't any JE to be posted until the GRN has been done or invoice has been raised, Am I right?

Regards

Sahil