You should be able to get early seating, either by asking to be put on the waiting list or once you are onboard. Just call or chat with DCL and you should be ok.
I can’t answer your main question. It haven’t seen an evening Cabanas visit in the Vlogs.
I’ve been checking daily for months for main dining seating for out 10.30 sailing on the Fantasy. It was available when I checked yesterday so I was able to change both of our rooms to first seating. We were waitlisted but I was able to switch it myself first. I suspect many cancellations are coming through with all the changes so keep your eyes out for availability
GET UP TO A $1000 SHIPBOARD CREDIT AND AN EXCLUSIVE GIFT!
If you make your Disney Cruise Line reservation with Dreams Unlimited Travel you’ll receive these incredible shipboard credits to spend on your cruise!