Perform calculation only when a certain date is reached

Hi,

I currently have a formula in F12 that sums cells F4:F11
In F13 I have a formula that checks if any cell between F4:F11 are blank, it won't calculate F12-30, and will leave the figure as 0

=IF(COUNTBLANK(F4:F11)>0,0,SUM(F12-30))

Essentially, the -30 is only calculated on the date at F1 (in this case 11/05/2013 Australian format as DD/MM/YYY)

If there a way that I can keep the above formula, but also add in a date requirement?

Example: IF F4:F11 are blank, AND TODAY()<F1, display 0, else sum F12-30

I have tried =IF(AND(COUNTBLANK(F4:F11)>0,TODAY()<F1,0,SUM(F12-30))) but I get a "#N/A - wrong number of arguments to IF" error

Kindes regards