They really should bloom the first season. Cannas started from seed will often bloom the first season, so rhizomes should definitely bloom. I bought some from Lowes & Home Depot this year, mine have all bloomed, but not as much as I would have liked. They really like hot weather & lots of water, & we had a rather cool spring here this year, so they were slower to take off. I believe lots of people plant them with bananas

My Canna had lots of sun, water & organic matter. They bloomed continuously from May till now. Some of them, I had to move from direct afternoon sun, but they still had a lot of heat (black plastic pots). The one I had planted in a concrete pot, bloomed, but not quite as profusely. I had nine different varieties purchased from neoma's garden (e-bay) this year.

Grown with good care, good light, and heat ..cannas should have no problem to bloom midsummer thru fall.
Alice