Depending on your subscription, you may not be able to use only Bulk Extract for this particular scenario.
If your BE supports Smart Lists then run an extract on a corresponding SL.
If your BE only supports Static Lists then you'd have to run daily batch(es) to add people to a list. Then clear all the existing people in that list (or you could run that clearing run the night before, getting the order right is the point). Then extract that List.
Or, given the small number of leads, you could use the Lead by Filter Type export (as in fact Bulk Extract is quite complex to reliably automate, if you're not familiar with building that kind of logic). Copy your Date field to a String field whenever it changes, then that "stamped" date-like String can now be used as a filter.
Alternately you could copy