A method, apparatus and product including: assigning geographical zones to a mobile retail unit based on first user segments of customers from the geographical zones and based on second user segments associated to an inventory of the mobile retail unit; based on the mobile retail unit being located at a location in the geographical zones, detecting a first group of customers within a first distance threshold from the location; sending a first set of order invitations to the first group of customers; determining to adjust the first distance threshold based on a delay probability; based on said determining, increasing the first distance threshold to a second distance threshold, wherein a second group of customers are detected within the second distance threshold; and sending a second set of order invitations to the second group of customers.