Newbie question regarding bloom time
I have no experience with dahlias other than the potted ones I bought last week. I've instantly fallen in love with them though and can't wait to try new ones next year! The ones I have are already in bloom, although I've read that most dahlias hit their "bloom stride" in August and September. Does this mean that I should expect no blooms until then, or does it just mean that I'll get a few, sporadic blooms in July and then tons in Aug/Sept?
Also, I live in zone 5 and we can have a frost as early as the first week in Oct. Does that mean that if I get a late blooming variety that I might not even get a bloom? Should I only consider early bloomers? Also, I do plan on starting them indoors -- will that give them a jump start on bloom time so that I don't have to look at early bloomers only?
Sorry for the all the questions -- I just want to make sure that all my efforts will result in blooms that I actually get to see for a few weeks before Jack Frost pays me a visit! Secondly, our first baby will be born late Aug/early Sept and I thought it would be nice to plant flowers that would be in bloom for her on her birthday each year. I'd be so sad to choose some that would bloom too late.
Oh, and does anyone grow Spartacus? I am interested in trying it, but can't find any info about its bloom time -- early, mid, late? Is it a reasonable assumption that it is a later bloomer since its flowers are so big, maybe it needs more time to develop them? Or is that totally misguided? TIA!