Add check on date available for product to existing checkout

When a customer CHOOSES 'Will pick up at store' - it calculates a date based on todays date that the product will be available for pick-up... BUT there's one (very important) exception that I forgot about... Each item on our website has a date available field. On a typical WEDNESDAY/THURSDAY we are logging in product that is due in NEXT WEDNESDAY. So this 18th & 19th we were adding product to the site that is not due in until the 25th. In the case of those products the system will need to check the cart - see if any product is dated in the 'future' and let the customer know the order will not be available until that following FRIDAY. This will require more code and I realize I never mentioned it so it will cost extra. Let me know how to proceed as I need this taken care of as soon as possible... Waste of your time to bid on this unless you are the person who started this job - I don't know how to just award a project to a person and skip the bidding game.