If you're flying in on BA, you'll avoid the main immigration hall at MIA which will shorten the wait time considerably.

That being said, 2 hours is not long once you've touched down, taxied, waited for the jetties to be attached, and offloaded - all assuming you land on-time which is never a given.

Queues at customs are long-gone so nothing to fear with that aspect.

Your bags should, I think, be checked straight through as it's something they do specially at MIA.

From there you'll take the elevator up one level (it's slightly to the right as you walk into Arrivals) and go through security at Margaritaville (which will be just by the exit of the elevator).

M