Never? As I posted above, I sincerely doubt that they'll have any PS5 exclusive titles that are up to their recent standards. One or two smaller titles, perhaps, but nothing breathtaking. That's actually pretty typical for console launches with the usual exception of one incredibly strong Nintendo title at launch. The Xbox 360 didn't exactly launch with a stellar first-party lineup (Perfect Dark Zero was pretty awful and while Kameo was surprisingly solid it was small in scope.) That was definitely Microsoft's best showing in a console generation to date.
This generation is looking like it might be a little different for everyone. It's the first time we might see
true cross-generation titles, a single SKU that can take advantage of the new hardware while still delivering a solid experience on the prior generation. With the exception of the single SKU aspect, It's the trick Nintendo has used twice now to give us a memorable launch title, first with Twilight Princess and then with Breath of the Wild. Halo: Infinite looks to follow in that vein.
Will Sony do something similar? It's impossible to say for certain. It could well be that Ghost of Tsushima winds up launching alongside the new hardware. Or that the big unannounced PS4 title we've heard hinted still remains to be announced is the one that will serve that role. Or it might be that they saw strong sales of remasters early in the PS4 cycle as a sign that it doesn't really matter when the titles first come out, so long as something big budget like The Last of Us Part II, Death Stranding, or Ghost of Tsushima is patched to showcase new capabilities of the new hardware. We've even started to get
hints from other developers that they may have something similar in mind.