How long does it take for them to reach flowering from seed? Also could they achieve so while in a large pot?
I don't have an answer for you. However you should be aware that its seed is monoembryonic and zygotic and thus will not grow true to type.
Ichang papedas are a smaller natural growing size (when on their own roots, not grafted) than other citrus, so they will likely begin bearing sooner. However, on the other hand, Ichang papeda is a bit of a slower growing species. It will also of course depend very much on the growing conditions, climate, if the plant is being overwintered inside. I would imagine they could start bearing when they are 75-90cm tall. I don't know if they require a pollinator to bear fruit (like a few citrus species do).
I do not answer from my own experience, but, according to this website At What Age Does a Citrus Tree Start to Produce Fruit? (Citrus)Trees grown from seed require seven years or more before producing flowers and fruit. They do not mention any exceptions.
That of course is true, but citrus trees with naturally more dwarfed growing habits, like kumquat, take somewhat less time. Basically the more dwarfed it is (like if it is on rootstock, especially dwarfing rootstock) the sooner in its lifespan it will begin producing fruit. Ichang papeda is one of the smallest growing citrus species, at least compared to all the normal varieties we are familiar with.
