You could set the Format of the Field in the Table to be /1000, but the problem with that is that once you get to record 1999 the next number would be 11000. If you set the Format to be 0000 in the table then the numbers will start with 0001, but they will roll to 2000 after 1999, so you might still have to import 999 "false" records before starting with 1000...