OK, my experience is turning out differently.
At first I started doing the linking using the phone app and things seemed to be mostly OK.
I then started doing everything using my PC and browser. Still OK.
Bands arrived on Thursday, but not having them didn’t make a difference.
I’m slowly adding in the Fast Passes and things are still smooth.
The downside for Fast Pass + is that you can only schedule in one park on any one day and you max out at three. On the other hand, if you only ask for one FP+, you get set up for two other “recommended” attractions.
I talked to a phone CM today and he explained that all of these limitations will probably go away once they roll out the full system and go live.
One other down is that you can not schedule FP’s for your check out date or later and certainly not before, even if you’re going to be in town andh ave an AP.
Edit: Looks like I might be wrong about the rest of the week after I check out. I scrolled to the right and found W/Th/F/Sa/Su were there for me as well.