Competent cells for transformation - (Jul/24/2008 )

wat is the ideal time to incubate cells on ice after calcium chloride tretment to make sure they are competent for transformation?
Is there an way to check if cells are competent before transformation?

I don't think incubation times after CaCl treatment are very different from normal transformation protocols. If you make a batch, just check 1 or 2 different aliquots for transformation efficiency. I don't know any other way to check.