There is not nice way. It comes from the EcomPeriod table.
You could import all products using ProductNumber/SKU to the ecomperiods table with the start and end date in such a way you get a record for each product with a publication period in ecomperiods table. Then use the ProductNumber you provided as the ProductPeriodID.
That should do the trick...
Alternative is to use custom fields on the product and filter them out in the index.
Okay thanks for the workaround. The customer also have the DW (PIM) so what about making a query in DW (PIM) and then bulk edit the products width start and and date? is this possible in 9.4.x ? then maybe I can persuade them to do this when we upgrade :)