It's clear from the mishnayos in the eighth chapter of B'choros that one is capable of redeeming his firstborn son before the latter is a month old. (For example, they discuss whether the kohen must return the redemption money if the baby died after the redemption before the baby turned a month old.)
Considering the redemption celebrations that people make on such an occasion nowadays in the United States, and considering that sometimes it would doubtless be more convenient to hold such a party on one day than on another for a variety of reasons, I'm surprised that I've never heard of a redemption being held early. Why not?
 I haven't studied that g'mara.
 Not right now, during the COVID-19 epidemic, but more generally.