Single or both groups of final

Ofcourse Both, If you ask me then half battle is already won and the results no matter what level is your preparations will always be as per the ICAI, What you could do is complete FR, SFM and Costing in one bunch preferably morning and make another bunch of Law , Audit , & IDT and ISCA which is mainly from a Revision perspective. At night devote daily 1 hour to DT, and make sure what you learn at day n you keep on revising it at day n+1,n+2 ....