Generally speaking, most manufacturers will require anywhere between a 20' container to 40' container in order to private label, due to the high costs of creating and packaging your own brand. As a general rule, the first container or two are usually just breakeven for the manufacturer, with the hopes that more sales are on their way.
However, like tomcat explained, it all depends on the contract that you have set up with the manufacturer. Sometimes we can be flexible based on the outlook of a particular client, sometimes not.
There is a possibility as well, depending on what types of packaging you are looking at, at putting together a "mixed container" of different sizes and blends (regular coffee, instant coffee, capppucino, etc) and working out a longer term deal to supply those and give the client a better mix to sell.
All we do is manufacture for private label, so if you need any more specific information, you can always feel free to contact me and I'll try to help the best I can.
Best of luck to you.