Can anything in the future tense be a proposition? How I learned propositions is that: if we don't know, then it is not a proposition.
For example, x = 1 is not a proposition. But, let's define boolean x = (tomorrow whether or not the event occurs). So, 1 = event occurs and 0 = event does not occur. 
Thus, my English sentence translates into (x = 1) := (tomorrow = event occurrence)
I'm in some disagreement as to whether or not future-tenses are propositions. Please confirm this reasoning or not.
 A: 
"How I learned propositions is that: if we don't know, then it is not
  a proposition."

There are plenty of propositions, including mathematical propositions, of which we do not whether they are true or not. For example, take $N$ to be your favourite very large prime, and consider the proposition "$2^N - 1$ is prime" (Unless you are an ultra-finitist!), that's a determinate proposition, being brute-force decidable in principle, but we don't know whether it is true.

" x = 1 is not a proposition"

Yes, ripped out of any context, it isn't a complete proposition: but that isn't an issue about knowledge, it is an issue about incompleteness.

"I'm in some disagreement as to whether or not future-tenses are propositions."

Tenses aren't the sort of thing that can be propositions, though being future tensed can be a property of some propositions. (We might reasonably hold, though, that purely mathematical propositions are tenseless.)
Perhaps you are confusing the issue about whether there can be future tensed propositions (like "there will be a sea-battle tomorrow"), with the quite different issue of whether a future tensed proposition can have a determinate truth-value now, before the time it is about (a debate that goes as far back as Aristotle, whose example the sea-battle proposition is).
