Things taste different when made in small batches rather than large and commercially processed batches. When you make things in large batches, you end up changing the chemistry. Therefore, it is best to make your jams, jellies, and pickles in small batches. You'll need to carefully plan out your supply purchases and your cooking schedules, but small batches also mean you aren't going to waste anything if it doesn't sell fast.
Also, most jams and jellies reach their peak flavor within days of being sealed in jars. If you prepare too many in advance, people aren't going to be able to enjoy these flavors if your jars sit around for a while before getting sold. It will also allow you to preserve the brightness and color of your food. Food that looks and tastes better is the key to repeat customers and profitable business.