In all honesty, Ishida is doing what he wants XD Giving us this ending in TG and not telling his fans about it- the rage and disappointment was short-lived, but damn, he really trolled his fans in these few weeks after the ending.
He took about a little bit more than a year before he introduced us to Shironeki/White-haired Kaneki. Didn't care that a lot of people thought pre-Ch.60 people was boring and slow-paced (which I disagree with b/c I still love Kuroneki a little bit more than Shironeki). I don't think the transformation with Kaneki would have been as effective on the audience if Ishida hadn't let us get used to black-haired Kaneki a little bit longer.
Same thing goes with Sasaki. The longer we wait, the more we are dying to see Kaneki regaining his memories. And when the time comes (most likely not in this arc), fans will be hype as hell after all this waiting. The one thing I give Ishida though is to have revealed to his fans early on (Volume 1) that Sasaki is indeed Kaneki. Otherwise he would have lost a lot of fans b/c many don't feel the need to follow a new MC.
Honestly, my thoughts about it are thus (bonus points for sounding like a sir right there

):
I'm kinda confused as to why people are differentiating Haise from Shironeki and Kuroneki, as if any of them possess different base characteristics. There really isn't much difference between either of them. Take Shironeki. He exhibited the same character traits as Kuroneki, kindness, gentleness, respect etc. The only real difference between the two was that Shironeki's chaotic side was more pronounced, he was willing at that point to slip into a chaotic state, whereas Kuroneki was resistant for longer, until he absolutely needed to bust loose. Haise has the same personality type as he always did, there's only minor differences. When it comes to disposition, he's more resistant, just like Kuroneki. Also, instead of Rize's instincts whispering in his ear as they did Shiro and Kuroneki, it's Shironeki that's whispering.
So imo, there really is no difference with when he gets his memories back, because it's not like he'll cease to be Haise and continue to be Kaneki, the man is and always has been Kaneki. The only thing that's going to be difficult is navigating through his situation with his memories, as he's in a different place than he was previously, i.e. the CCG.