Are the Periods in FinancialAccounting&Controllong driven by system date?

Hi Experts,

Our Finance Department wants the Period roll-over on Wednesday, 24.12.2008 (Close period December 2008 and open period January 2009 period on the same day) in Financial Accounting&Controllong modules.

Are there any consequences in doing that?

Are the Periods in SAP (FinancialAccounting-OB52 & Controllong-OKP1) driven by system date?

Normally, we will be performing Period roll-over on 1st day of every month.

Please help...

Thank You,

Nagarjuna Palnati