Tracing Finished Goods

We produce product continuously for ~3 days, in which all the boxes contain the same lot number. However we are trying to identify which product was produced on each day. We preprint labels for the production run that contains a "master lot number". Any ideas on how to go about identifying the product produced on each day? Any help is appreciated! 

One option would be an online printer that labels each pack with date and time.

What are you producing?

I'd say something easy, keep it simple: use one of those smaller label makers to run off a bunch of tiny date stickers.  Heck, you could even have the employee palletizing use one of the grocery store price sticker guns to tag each box with that day's date.

Add the Julian date to the master lot number and only print as needed for that day

We produce food ingredients, which go in 50 lb boxes. We can do as many as 300 boxes per day.  I like the idea of just printing what we need for the day..but I don't know about production. 

how hard can it be for production----seriously

Delegate the task to someone to run them of daily-----the printer does not need babysat while it's printing