I've just used Alclad chrome for the first time, pretty impressed with the stuff, I've left them to dry out for a week, but I will probably leave them a little longer, as I've been told the paint takes a while to dry out, if this is true or not, I don't know.
I followed the advice and primered the bumpers first, followed by a few coats of gloss black cellulose, then a few coats of Alclad, sprayed on at around 20 psi, if you don't have any luck, I will do them for you, as I still have the door handles and boot handle to do on the Mini.