Although I have not had experience with tiger lotus babies, some general guidelines should be applicable. If you are not sure when to pull off the babies, leave them attached to their parent leaves and see how they grow. They may detach on their own, or they may get bigger and bigger and get their own roots in the gravel. In general, they can be detached when they have both roots and leaves. The production of new plants very likely does not mean that the parent plant is about to croak. Instead, it means that the parent plant is healthy.