You can run the Fiscal Year Change before you complete the month end or year end close.
The fiscal year change is only a technical step and it makes it possible to start posting in the new year. It doesn't effect
the results of any of the other things you mention. It is quite common to start posting in the new year before year end closing has been performed
Normally we keep 2 yrs open in Asset moudle. when start the new fiscal year, we have to change the fiscal year otherise we cant post the new asset acq.enty. AJRW is the fiscal year change Tcode. After complete depreciation posted, then only u use the AJRW,
Tcode OAAQ - to check which year is closed