Event Challenges need 24 hour gap in between?

Does anyone know what the Devs mean when they say only one challenge can be completed per day?

I completed the first challenge at 11:15pm last night because they gave us no warning this event was coming… not even a day… and I found out by chance from some youtube video i was watching. So now its 9am the next day and I cant do the next challenge yet… Does that mean I need to wait 24 hours till I can do the next one?

The problem is that means that ill have to do all of my challenges at like 11:20 or later and QUICKLY if I want to fit all of my challenges in before the dead line?

I would have just liked maybe 10 days - 2 weeks to do the challenges, or at least some warning they were coming.

Side Note: like another forum post says, why are these portraits not visible in lobbies? if that stays the case these are worthless rewards anyway so no big deal.