Close Process - Create Income Statement Closing Journals

I have a question if I wanted to run the “Close Process - Create Income Statement Closing Journals” request to create the carryforward adjustment journal entry in the last period of year 2011.  I realize that this program should be run only after the last journal entry for the 'ending' year (for example, 2011) has been posted.

My question:  Must I not open period 1 of the new year (for example, 2012) until I first run the “Close Process - Create Income Statement Closing Journals” request and post the rollforward journal entry that it creates?

What happens if I open period 1 in 2012 before creating & posting the journal entry created by the “Close Process - Create Income Statement Closing Journals” request for the last period in 2011?