Yes, I would think waiting until the clump matures would somewhat muddy the picture for the reasons Maurice noted - I have seen how once-connected fans eventually establish their own root system and disengage from the original fan. At that point, I don't see how it would be easy to say it is a sport unless it reverts, in whole or part, back to show the original flower. And, if that occurs ... that may also mean it is no longer a sport (its reverted).
Also you noted earlier in this thread that is is about 7-8 mature fans ... were they fans that blossomed earlier for the friend who gave them to you? If so, it might need AHS to determine who would be considered the originator?
Even the type and duration of evidence needed to establish sport or split would need to come from AHS, and unless you find that out from them ealier rather than later it may be that you might miss an opportunity. Thus, the hopeful nudge to you that this may be an important cultivar ... but also that research (AHS) and actions may need to follow in a timely fashion if you are up to pursuing it.
