I asked about this very same thing earlier, in this thread:
http://groups.google.com/group/no-thirst-software/browse_thread/thread/8728753712c3918f/6e81f59476453841
It's not possible at the moment, but Kevin states he is looking at
improving the process for managing future cash flow. However, he
indicated it won't appear before version 2.
For me, it was far more important to have my buckets deducted early,
so I could compensate while there was still money in other buckets. I
don't have any repeating transactions, but since most of the
information is memorized, and keyboard entry is so fast, it's not
terribly painful to make an entry each month. Also, there's some extra
effort involved in changing the date for those months when the
transaction cannot fall on the regular day, or in changing the amount.
//Drew