My husband doesn't like all the 2am wakeups but since we stay in a studio, so he doesn't really have a choice when I'm running Dopey. But this year we came back from the races and took a nap most of the days (set an alarm for 10 or 11am, but always woke up before it went off) and it was fantastic.
The biggest thing to consider for "when should I get to the start area" is that there are now corral closing times before the race starts, and if you are in a faster corral you need to be there sooner. And also, how much would it suck if you waited longer and your bus went the wrong way, or they closed a road early (which definitely happened at one of the races this year) and you have to re-route to get in. It's also about 0.75mi from the bus drop off point to the start area. And if they go back to the 'old' start area for the HM and M, it's another mile walkout to those corrals (but I don't see them doing that since there were no obvious issues this year with the new parking-lot corrals.)
That being said, I feel like if you can be ON transportation by 3:30, you should be good for most of the days (maybe a little sooner for the half/full since there might be a line for the monorail)