I know I’ll draw a lot of flak for this, but I honestly think NFP wasn’t intended to let us get married when we want to, just so we can get all the “perks,” and do the baby-making stuff later. Having babies is part and parcel of what being married is about … so if you’re starting from the outset saying you’re going to wait years, you’re not doing all of your vocation as a married person.
This is my opinion, as a pregnant newlywed (conceived a month after the wedding), and I know not everyone will agree with me.
But on the practical side, I have known tons of people who got married with the plan of using NFP for a year or two because they couldn’t afford a baby, and next thing you knew they were pregnant! Most newlyweds do find NFP difficult, either because of their desires or because a woman’s body acts a little different when she’s married and she misses the signs. And there’s always that 1% failure rate … so unless you have the basic capacity to pay for the possible “mistake,” you shouldn’t get married.