If I am following you correctly, I agree, Jesus indeed answered the "when" and it seems that just knowing English is enough to clarify this:
Merriam-Webster:
"this .. the person, thing, or idea that is present or near in place, time, or thought or that has just been mentioned"
Truly I tell you, this generation will not pass away until all these things have taken place. (Matt 24:34, NRSV)
Merriam-Webster
"that .. the one farther away or less immediately under observation or discussion"
"for forty years. Therefore I was angry with that generation, and I said, ‘They always go astray in their hearts, and they have not known my ways.’" (Heb 3:10, NRSV)
"This generation" clearly refers to those to whom He was speaking, Mt.24:34. "That generation" refers to those many centuries farther away, Heb.3:10.
No way can I read Matthew's use of "generation" and understand anything but people in a certain time frame, contemporaries and the first use in Matthew 1:17 sets the meaning right at the start. To say this means "race" or "kind" as Matthew uses it is absurd.