I hope they will visit the Commonwealth nations - especially realms - before visiting anywhere else (that is if Charles is serious about his commitment to the Commonwealth).
Yes, I agree. I think that we can expect visits to Canada, Australia & New Zealand within the next two years. A visit to the Caribbean realms will be last, and only after those countries have had time to determine whether they wish to remain realms or become republics. I haven't really seen much news or discussion about republican movements in Papua New Guinea, Solomon Islands & Tuvalu, so if they're content with remaining realms, I would expect a tour of those three countries to come after the Canada, Australia & New Zealand tours.
As far as Belgium is concerned, as others have noted, they have not had a State Visit to the UK in 60 years, so it could very easily, along with the postponed State Visit from Japan, also happen within the next two years, and it would make sense for those to be scheduled sooner rather than later.
I don't see Charles & Camilla making any official State Visits to the European monarchies, the US, France, Germany & Italy until after the Commonwealth visits are completed. We're going to have a good decade of major State Visits both to and from the UK, if not longer.
Leonor's 18th birthday also comes next fall, most likely after Charles' coronation, so that might be the next major royal event, depending on how big of a deal the Spanish RF makes it - probably not very, knowing how lowkey they are, lol.