Thanks peekay.
Max-
there are various websites that offer a prediction of where and when.
Indeed the previously mentioned "Heavens above" is a good 'un.
Heavens-Above
For the unitiated I'd say if you're looking for the bright iridium flashes using that software (and no doubt all the others) it's worth making the effort to put a really accurate position in, rather than a generic "nearest town" or even village. it is interesting to see how narrow the iridium flash ground tracks are and a handful of Kms of position error can make a big difference between a predicted event being a "wow" or a "what, that's it? but you told me.....".