Allow adjustable start times for Zeno polling
For goals which require bigger chunks of time to progress on, it might be useful to get warning messages 2/4/8/... days out.
E.g. if my goal is "spend two hours a week meditating", and I've committed that all my sessions must be at least an hour, then on an emergency day I still need to find an entire hour spare rather than 2/7ths of one. Knowing that the deadline is coming a little further out would help me manage multiple time-intensive goals deadlining around the same time.