The Brazilian cherry will darken considerably, as does American black
cherry. Whether or not it will blend with the rest of your house's
flooring is less of a certainty. It should come much closer in a year
or so--I seriously doubt 6 months. Much depends on the amount of
sunlight hitting the wood. If it's in a closet, or protected from light
otherwise, the changes will take longer.

A lot of woods change color dramatically over their lifetimes if left
unstained. Black cherry is one of the most remarkable; walnut lightens
(cherry and walnut tend to pass each other during the changes).

And, of course, to the unthinkable: wood can also be stained to match
existing wood.