i guess i should clarify that my children are canadian and we went to live with my husband while the paperwork was going thru and a few months after... so their transitions were different in nature and i have little input other than what i've given for the whole immigration and adjusting to Canada, but i know about adjusting to Jamaica and am sort of applying the logic in reverse if you will...
and yes, congrats can-indy-jam... exciting times!
as far as food... my Jamaican nephew LOVED it when i made "canadian food" (french toast, grilled cheese, etc) for him... so just feed him whatever your children eat and it may just be a treat to him too
i find that many Jamaican kids, even the spoiled ones, will eat what is put in front of them because that's what they are taught... turning up ones nose at food is not only bad manners, but wasteful... i think have a better idea that people go without and they should appreciate the fact that they aren't one of them...
at that age in general, kids adapt quickly if they are open to the idea... my daughter jumped right into her jamaican school life, had a dozen best friends by the end of day one (and probably as many haters with her "tall hair" lol).... in toronto you have a lot of multiculturalism which will make it even easier for him to adjust IMO (there will likely be others that look like him, or maybe even are from Jamaica, or at least have Jamaican family)... my children were the only mixed ones in their school, and you probably know jamaican kids can fass, so they couldn't just blend in and be inconspicious to just "feel things out" if they tried.... he will probably have more of that option to play things a shy if he wants and be outgoing when he's ready... chances are he'll do just fine
nice that you were able to meet the great grandmother... those pictures will be cherished!