It depends on the variety. Some varieties take 90 days to produce fruit from seed, others take 120 days. Bloom is also influenced by the amount of water/food/sunlight the plant receives. Also, it's a curcubit, so it has male and female flowers. Male flowers tend to form first and these do not produce.
eight hours
12 years
~4 months
A watermelon typically takes about 80-90 days to grow after flowering.
1 year
two to three days
the bees that get the pollen produce it all back but not all they take and thats how flowers die
If planted from seeds, it can take several decades for the plant to produce flowers (it depends on too many factors to give a definite answer). After that, flowers are an annual occurrence. If you want a plant to produce flowers, buy on from a greenhouse that already has produced flowers.
2 days
It typically takes about 2 to 3 months for a watermelon flower to develop into a fully grown fruit.
Forget me nots take about a dozen days to germinate. The first year it grows leaves and the second year it will produce flowers.
Pumpkins typically take about 75 to 120 days to grow after the flowers bloom.