Well, you don't have to be dishonest, but then you don't have to put all your cards on the table before the first date either!
Good advice from CD. Please don't get asked on a date and say,
"Well, okay. Before we go, you should know that I won't have sex until our honeymoon
and I would like to have as many as 3 children before I reach 40."
But, discussing values on one of the first few dates (even the first one) and mentioning
this would save you some trouble later. I would recommend a second or third date for
such a specific, as a direct question from the man would seem too forward, so I would
guess the reverse, a forward statement unasked, would seem too much on a first date.