Field help (GAFDAT) 

The start date represents the date of the first recurring journal entry, as well as the start date of the frequency calculation.
The end date limits the calculation of the recurring journals

SEEWARNING The user should always check that the range is wide enough, to within a day, to cover all the open items of the recurring journal. For instance, within the framework of a "1 month" frequency recurring journal, if the start date is set to the 11 January, and the end date, to the 2 February, the system will only generate one monthly payment. There would have been two monthly payments if the end date had been set to the 11 February.