I've mixed some tobaccos and tried right away and couldn't taste anything.
2-3 weeks later and "hello" there you are.
Some will taste like perfume, chemical, just plain sweet, fruity, nutty, or just plain nasty.
There are some exceptions, as I think "some" of the alcohol based tobaccos blend faster.
Heating will help a lot, but still need some additional time.
If your tobacco doesn't taste good after 4 weeks, dump it...