From what I've seen it's mostly random... I've woken up to new EDDs, I've also had new windows show up around dinner time. I would say that I generally see them earlier in the day pre-noon (EST).
I used to see my changes after about 9:15 eastern. i think those were more for batch updates - 4 weeks, me clumped in with a bunch of others. i think more specific soft or even hard updates can come any time - i got my latest vin between 5:38pm and 9:30 p.m. (i was busy so coudn't check the app every half hour).
i will say, as the S starts to get more real, you can actually look for emails and texts (today i was texted, but not emailed, about my insurance info, which i previously supplied anyway).
mind you, once you get a vin, you don't check less, i'd the opposite, now whenever i have a chance i check the app - it's like breathing - i want to know when i have my delivery date (however, last time the text made me go to the app, and then schedule the date) - and even then, i was checking every few hours, until i saw the vin and delivery appointment disappear.
so, in conclusion, like voting, vote early, vote often; check early, check often
edit: PS - I think the updates are almost ALL automatic, so they could happen any time. I think the soft and then hard matches update based on events, logistics, etc. - so if a car gets to the location at sunday 9pm, i think it is possible that can update the system. ditto production for a VIN, etc.