When to put a good dog up for breeding?

I like to breed young, not wait until they are 5-6 yrs old because no matter how many years you hunt one before breeding they are not "proven" producers until bred and pups from them used, so here a young dog sayyyy 1-2 yrs old and showing to have and use all the tools in a better than average fashion will likely be bred if pups are needed. I have saw some really good ones from a long line of really good ones that just did not produce well and if you have waited until they are considerably older "with all your eggs in that one basket" you could wind up without. Trying to breed and maintain a line of dogs we don't want to wind up without.
As long as they are physically able to go I never put one up permanently just for breeding purposes, I just won't feed one I can't use for fear of something happening to them.