Killing Hitler...Possibly a time travel book

I remember a book where we meet Hitler as an unpleasant young man, but not someone likely to be a mass murderer. I believe it is a time travel story, but I can't remember specifically. In the opening he's living in a cramped apartment or maybe just a room in a house along with a Jewish man. I know it's a lame description, but that's all I remember. I think the word "Morning" is in the title. I know I read it around 1993. Been trying to remember for years!

Thanks for your help.

Yes!! I kept thinking it was Oleander Morning and could never get a good search going. Thank you so much.

Sarah C.