A growing fan will produce new leaves from the centre. Immature fans are or should be growing. How long the fan must grow, how large it must become or how many leaves it must grow or how large the leaves must be or the crown must be before the fan can produce a scape depends on its growth rate. A fan's growth rate will depend on its genes, on the amount of sunlight, the amount of water, the temperature, the various amounts of elements (fertilizer - nitrogen, phosphorus, potassium and the minor elements required), how much of its resources it is putting into producing seeds, etc.
In my garden, with no added fertilizer and no added water (just natural rain) and low levels of weeding plus high levels of seed making a fan will need at least one growing season (or more or less one year) to grow large enough to produce a scape and sometimes more than one year. If it is small enough when it arrives here after purchase it may not flower that year or the next year even without making seeds.
How quickly a fan can flower may also depend on whether that fan is all alone or whether it is attached to one or more other fans. The other fans may help the new fan by providing it with some resources to grow more quickly.
