Originally Posted by ChshreCat
If you have a starter that's been growing, I'd pitch it. It'll multiply in the beer just as well as the starter and you won't be leaving your wort where a wild yeast or bacteria can get a foothold. Can't see stepping up a starter while your wort sits being worth doing.
Chesre's right under normal brewing situations you want to pitch the yeast asap, and an active starter, even if it's not at the volume you would like is still better than no starter....or waiting and risking infection.
However some folks do "No Chill Brewing" and they don't pitch til the wort has cooled down to pitching temp, and that may be a couple days.
BUT they don't put it into a typical fermenter. They use something similar to a plastic jerry can, called an aquatainer. And what they do is pour the still boiling wort into the container and seal it up. The boiling wort instantly sterilizes the vessel, and after they put the stopper on the cooling wort forms a vacuum in the container which prevents anything from harming the wort. It's sort of like a rudamentary pressure canning of it. And it keeps it sterile til they pitch the yeast.
It is nearly impossible to recreate this in a normal bucket, with normally cooled wort. That added vacuum doesn't get formed...so your wort is at risk.
If you wanted to do no-chill and hold off pitching til you build your starter, then I'd say go for it...but storing it in a bucket, or carboy, that you couldn't pouring boiling wort in and instantly sterilise...then no, I personally wouldn't wait...I would just pitch what I had.