Usually the orders are filled within 1-3 working days. With the 4 orders I have done it has never taken more then 2 days to ship. They will send you an e-mail the night they ship so you can track the shipment and make arrangements to be there for the delivery. If there is a specific day you need this shipped you can add it into the special instructions section.
To guarantee a shipment on Friday you should order now and specify your requested shipment date.
BTW, you also mentioned you will be receiving another shipment at the same time - be careful not to add too many fish at once. You could set off a mini cycle.