What happens to New Tax Books if I convert assets into New Oracle CORP books mid-year?

I've read that the recommendation is to using Initial Mass Copy into the last period of previous fiscal year.  But, if the CORP books are populated mid-year, my only option is to load mid-year into the related tax books.  I have the tax information in another set of tax books (making calendar change by loading into newly created books) that have a fiscal year JAN-DEC.  New books are JUN-MAY.  If I load into DEC-16, which would be last fiscal period of pervious books, into new tax books that show JUN-16 as first fiscal period, what problems am I going to