Proper word for "Before including Current" value
I don't think you're going to find a single word, but you can shorten the phrase.
Note that it should be dates (plural) because more than one is acceptable.
Valid Issue Dates: 10-4-2018 and earlier.
(I only just now noticed the comments that mirror this.)
The only other way of expressing it is if you do something like this:
Issue Cutoff Date: 10-4-2018
Most people would understand that a cutoff date is a time after which something is no longer accepted. It's like a deadline.
However, it may not be as immediately understood by everyone as the earlier version.