Yes, you can leave it open for a couple of weeks (and most do); however, any entries made (even those with new year dates) will update the vendor account balance statistics for the prior year (i.e. ending 3/31/2008) when Year End is run.
If this is a concern, you might not want to enter any new year transactions until after you've decided to run Year End.
The new year transactions, even if fully paid, wouldn't be cleared yet as their date would be after the date you'd specify as your transaction clearing date.
_________________________
Regards,
Softrak Tech Support