Can I make juice in advance?

Different types of juicers keep juice fresh for different lengths of time. Masticating juicers will usually keep a juice good for 72 hours where as a centrifugal juicer will keep your juice good for 24 hours. Your instruction manual should tell you how long it'll stay good. If you need to freeze some for advance, only leave it frozen for 10 days; no more. Of course having fresh juice is the best way to get all of the nutrients, but most people need to juice ahead of time to fit their schedules; this is okay.