Just based on my observation in the last 2.5 years here ... MIA is very senior at the top. However, the bottom 1/4 or so seems to be a revolving door, so, if you get 75/6 in initial - it’s not unrealistic to expect MIA either immediately, or within the first 12 months. You’ll be doing S/Central America midnight turns or night domestic sort lines out of the same 4-6 airports... and that’s about it.
Chilling at home on reserve? Or the South American booty tours? Get in line... it’ll be a decade+ minimum..