Mine took about 8 years to get its first flowers. Harry's took over 15 if I remember correctly. But on the other hand, I know someone near me that only took 3 years. All were seedling trees.
The trees can flower all throughout the year. I've seen different trees flowering or fruiting in FL all throughout the year. I think it may be possible for one tree to flower and fruit continuously throughout the year.
With all that being said, the bugs are horrible. From an entire tree you may only get a handful of good fruit because almost every fruit will be damaged and possibly full of worms.