My amesiella bloomed with about a 4in leaf span, maybe less. I would measure it but the lights are off in the terrarium. I can get back to you with the exact measurement if you would like. It is potted in a 2in clay pot and the roots have since grown out of it quite a bit. I missed my opportunity to repot it sooner, so I am hoping they continue to grown downward more so I can repot without any breakage. The roots are pretty thick so I have been putting it off. Maybe I will it will go on to a mount instead.
A couple of months ago I posted a pic. of mine in bloom. I grow it mounted, and the leaf span was a bit less than 12 cm. That was the 1st blooming. It's growing new leaves, but they are not any longer. It seems to take forever for them to finish their spike, but it's well worth the wait.
Okay thank you all for the replies! I asked this question because I saw one for sale online, but it only has a 2" leafspan. Sounds like it would need to double in size to be old enough to bloom (I think I'll wait to buy a blooming size one).