It's all up to you... for me, if the dog is showing stand out qualities at an early age, i.e. producing good hogs for you, then I'll go ahead and get a litter out of the dog before really "pressing the gas peddle" if you know what I mean...
I'm all for finishing out a dog before breeding, but when you see a stand-out specimen... you sure don't want to screw around and lose those genetics for a couple more hog pics...
But a dog has to REALLY show me something to breed them early...
an early starting dog with a ton of potential excites me and I will breed it on the first heat... especially if it comes from a long line of early starting dogs.