In January I took DH to WDW and Universal studios for his first time. He is NOT a morning person and usually he sleeps until around 10-11am when we're on vacation. For months before we left, I prepped him and told him how important it is for us to get up early to maximize our time in the parks. It took a while, but he eventually and begrudgingly got used to the idea that we were going to do RD at least once. With those expectations in place, we RD'd Magic Kingdom on our first full day there. He dutifully got himself up and ready, and we arrived in plenty of time for the Welcome Show. He's not really a "Disney" person (definitely not in the sense that we are here), but he wept!!! at the Welcome Show! We then marched into the MK and literally experienced ZERO waiting for about the first two hours. (I realize it's not always quite like that, but the planets aligned! And, to be fair, and had designed a very smart touring plan.) Well, after that experience he was SOLD. I was shocked when he was up and out of bed and ready for RD every morning for the remainder of the trip, including for 8am early entries at Harry Potter World. Once he saw the clear benefits of arriving before park open, he needed no further convincing from me. In fact, he is now advising his co-working who are planning their first visits to do the same! (I told him, Shhhh, keep it a secret...!)
Now of course your wife may not have the same reaction — but if she hates waiting in lines as much as my husband does, she might! I agree with the "just once" strategy as suggested by many posters in this thread, so long as you also have a really solid touring plan in place so she has a chance to really understand how awesome the benefits actually are.