If your son has been charged with Possession of a Controlled substance in the Second Degree, this is a very serious charge. It is a Class A-II felony. The penalties for a class A-II felony are steep. Upon conviction for this charge, on a first offense there is a minimum possible determinate penalty of 3 years and a maximum of ten. Alternatively, he can be placed on lifetime probation.
If he was incarcerated, NYS law requires that he be arraigned on the charges within 24 hours. If he has no lawyer, he would be assigned a public defender for purposes of his arraignment. If he is not indigent and can afford to retain a lawyer, the public defender would not typically keep the case beyond the arraignment period.
While the charges are very serious, you son was part of a sting here. Drug sniffing dogs are at postal sorting centers and UPS and Fed Ex centers, and when the authorities pick up contraband like this, they frequently follow it up. The delivery person is, in reality, an undercover officer, and once the package is taken into the premises, they can then send the back up team to arrest the recipient for possession of a controlled substance.
I cannot tell how strong a case this is against your son. I don't know if the package was addressed to him, for example or if he opened the package. Clearly, if it was sent to someone else at his address or if he marked it return to sender without first opening it, those would be facts which would be helpful to his case.