For a first offense involving marijuana and paraphernalia, the outlook is generally about as good as it gets in the criminal justice system, and incarceration is often not part of the picture at all.
Many jurisdictions have moved toward diversion programs for exactly this type of first-time, low-level drug offense. The most common is a pre-sentence intervention or pretrial diversion program, where the defendant agrees to pay a fine, complete a drug education class over a few days, and stay out of trouble for a set period. If he completes the program successfully, the charges are typically dismissed or reduced rather than resulting in a conviction and sentence.
Whether that option is available depends on the state, the county, the specific charges, and the prosecutor's office policies. Some jurisdictions are aggressive about diversion for first-time marijuana offenses. Others are not, particularly in states where marijuana remains fully illegal. The quantity of drugs found also matters. A personal use amount is treated very differently than an amount that suggests distribution.
The record piece is worth understanding clearly. Even if the case is resolved through diversion, an arrest record exists. An expungement, which seals or erases that record, may be available depending on the state and how the case is resolved. Some diversion programs come with an automatic expungement upon completion. Others require a separate petition after a waiting period. His attorney should be asking about expungement eligibility from the very beginning, not as an afterthought once the case is closed.
The first step is making sure he has an attorney who knows the local diversion options and can position him to take advantage of the best available outcome.