I think we started trying about four months prior to the wedding, as we were in our early thirties and didn't want to waste any time after we committed to each other. The timing was such that if we got lucky on the first cycle, it wouldn't be TOO obvious around the time of the nuptials.
Turns out we got pregnant three days before the wedding, and we didn't find out until after the honeymoon and its associated boozing and partying. In retrospect I'm glad it happened then, since my wife was ultimately diagnosed with hyperemesis gravitum (i.e. mega morning sickness, i.e. what Duchess Kate's going through right now) and her puking her guts out for the first trimester would've been the LAST thing we needed leading up to the wedding!
Anyhoo, this is potentially a huge problem for people two generations from now; I would hope a cause can be found, and that it's something environmental and hopefully treatable before it goes all Children of Men on us.