Hi, well mine has 15 and still has no flowers!....maybe more to do with my UK climate than size. Think it's just given as a general rule of thumb, in other words don't expect one with just a couple or so to be big enough to be able to produce a flower stalk. The more leaves the bigger the plant will be overall. Leaves are produced during the summer months and flower stalks over winter, so I have read. Also the new leaves emerge from directly next to the previous leaf, out of the fold of it's leaf 'sheath' at the botom of the stalk, and flower stalks emerge from elsewhere in the fan of leaves. So it's patience I guess...like with me still! Good luck.
Gill.

I think you are confusing the advice for getting Heliconia's to bloom with Strelitzia. In general, Bird of Paradise need sufficient sun, warmth and size to bloom well, but it isn't necessarily related to how many leaves a plant has. I have divided mature plants that proceded to bloom with less than 7 leaves, but the root mass and stored energy were comparable to a much larger, older plant, even after being divided.

lol greenclaws! I hear ya. I have one with that many leaves and no blooms yet. I have another, maybe with 9 leaves or so and it has bloomed. Don't know which is older-got them both at the same time at HD. I have heard they can take a long time to bloom from seed but I haven't started them that way because they are too easily available here. I only divided one of mine and it had a huge root mass probably larger than the plant.

Sjn, hi there, mine is fast outgrowing its pot and is screaming out for a bigger one so much so that the soil is ending up on the g/h bench as roots are pushing it higher and higher! Seems it has really taken off this season as its now growing 3 more leaves having put out five earlier this year. Also it split into three 'fans' of leaves instead of just the one. Pulled off several lower leaves as they have aged and were splitting away from the base. It was a weedy little £1 plant with 3 tiny leaves on a 'reject' trolley at a DIY store when I had it several years ago, I felt so sorry for it and decided to give it some desperately needed TLC, and now is almost 5ft high. Just wish it would flower!! Need to decide quickly whether to take the plunge and re-pot it even though its very late in our season now. Think I will risk it. Off to find a big enough pot!
Gill.