For espresso at least, the advice is to let it rest for 1-2 weeks after roasting. Roasting traps CO2 in the beans, and the aim with resting the coffee is to let some of it escape. It’s especially important for espresso but resting filter blends up to 2 weeks after roasting is becoming common advice too.

It's not like it falls off that quickly after that point either. It might not be ideal, but it's still more than adequate for a good while after that.

Though that's me preparing drip coffee. I'm not trying to get the perfect crema on a shot of espresso or something.