Yea, it is really - best time to divide is when you get them ready for winter, or in very early spring.

Ok thanks for that, they'll have to take their chances no then.

Agree, just enjoy it for now. Divide it in the fall after it dies back. Give it some fish fertilizer because it's probably very cramped in the pot now. Is it terracotta? Don't be surprised if the pot shatters at some point. It happened to me.