I didn't remember Carolyn Kunin's suggestion "that John Shade is the young miscreant that was judged by Judge whatsisname (next-door neighbor) with the alphabetic daughters, for having offed his parents when he was but a wee bairn."  This runs into problems with the timing.  The more important one, probably, is that Kinbote's statement that the little parricide was seven (n. 47-48) would contradict his statement that Samuel Shade died in 1902 (n. 71), which is when John was three or four.

Also, If Goldsworth was a judge when Shade was seven, Goldsworth must have been at least twenty years older, and even that small a difference seems unlikely.  However, he generally seems to be Shade's age or younger--they resemble each other, Goldsworth's daughters are much younger than Hazel, Kinbote doesn't mention any age difference between the "Medusa-locked" Goldsworth and his wife, etc.  If we assume that Goldsworth was only 27 when he sentenced little John Shade, then he would have been 66 when Dee was born and 71 when Alphina was.  It's not impossible, but it would be unusual enough to merit some comment from Kinbote.  And where do 27-year-old judges try cases like that?