Investors wondering whether to join the party in Brazil might already have missed the best of it.

The unorthodox presidency of Jair Bolsonaro, who took office Jan. 1, is off to a market-friendly start, on balance. Finance minister Paulo Guedes wowed Davos with his ambitions for all-important pension reform, needed to cut the nation’s budget deficits. He’s targeting savings of 1.3 trillion reals ($357 billion) over a decade, nearly three times the goal of a bill that died last year. Guedes should gain a key ally when Congress...