Not a bad pair for a woman to start with when she wants to feminize her husband. Smooth, not overtly feminine (you don't want to scare him, you want to ease him into it), and tight enough to tuck.
If you want to go for a set, at first forgo a bra (you'll have him in one later, don't worry), and instead try something like this camisole and panty set.
Again, subtle, it's like the tee shirts he wears, just a bit more feminine and flattering to his trim figure.
"Honey," you can tell him, "it's not that I want you to wear women's underwear, it's just that this set fits you so much better than anything in the men's department."
A couple of things. First, make sure you call the camisole and panty set 'underwear' not 'lingerie'. That may scare him off. Men don't wear lingerie, but they do wear underwear. Yes, he'll be wearing all sorts of lingerie, later, but start slowly. Second, make sure you continue to emphasize that you don't want him to wear women's underwear (yes, of course you do) but that he's doing it for a practical reason (better fit).
You'll move to more feminine colors, over time, and more feminine cuts and materials, for feminizing him, getting him into lingerie, is the goal. Just start slowly, remember, the frog will not jump out of a cold pot.
Again, don't worry, your ultimate goal is to have him looking like this every day: