Protip: you can come in to Brussels through Amsterdam. Passport control line in AMS is negligible (at least at 5AM, though I'm sure it's not  too bad at other times either), and it's only a 2h train ride straight from the AMS airport to Brussels.

That's a great travel tip! Amsterdam Schiphol is indeed a smooth airport for transitions and the train ride to Brussels is both scenic and efficient. Plus, you can enjoy a bit of Dutch culture before heading to Belgium. Worth considering for anyone looking to avoid long waits at passport control.