So maybe I still don't know the difference between Labor Day and Memorial Day. But in terms of style rules, it shouldn't matter anyway. I say white pants whenever you feel like it.
As long as we're not talking about some Boogie Nights roller rink booty shorts (not cute, Miley), there is absolutely no need to be afraid of white bottoms.
Not-too-tight white jeans + work appropriate top + any shoe you wouldn't wear to the beach. That's it. Instant Emmanuelle Alt vibes.