Where they come from doesn't matter, although, you may want to get the male from a different place than the females (this will ensure you have outcrossed blood). I would start with females being the size of a medium to a small large, and the male being a little larger. It might take a couple of weeks before you see babies, but you'll know that your females aren't used up, and that your male isn't in his last days. After all, breeding does take it's toll on the lifespan of a rat. I've read that most people feed off their adult females after about 8 litters. I think I read that people also feed off the males at about 1 year, and replace them with new/different blood.

Best of luck,
Anthony-