You can wait just as long as you don't let the roots on the keiki get to long. I had one and I was not sure how to handle it, this was before I found this forum. The keiki was blooming and the mother plant was blooming at the same time. I didn't want to cut if off while it was blooming so I waited. It got so big and the roots got so long it was hard when I did finally cut it off.
I had 2 sticks holding it up. The keiki was as big as the mother plant. When I did cut it off and re-pot it I put it to deep in the pot. It took it several months but it finally started rotting where the stalk met the medium. I have a post on here about it some where. My keiki died but the stinking roots still have not. Just be careful.
And my equestris is a keiki maker big time. It did take it many years before it did it but then it made 3. They are basal keikis though.
Yeah I wondered about that, I would think the keikis would start to get heavy enough to topple over the momma after a while. I'll keep my eye on this one and see how things go.