Sam,

A well-made jointer of any size is better than no jointer. When I opened my own shop I bought an old (1950s) 12-inch Northfield, but I'd apprenticed in a shop that only had a 6-inch Delta/Rockwell, and we turned out high quality work, as often as not running long-ish and wide-ish material (a bit of a struggle but doable on a 6" jointer). If you can buy more of a machine, do so, but getting something into your shop and getting to work is more important, IMO, that waiting until you have a bigger shop or larger budget.