magore I believe based on the reply from ZWO they misunderstood your question. I assume what you are asking is for a way to set up an observing PLAN for that evening sometime earlier in the day, when the object(s) you wish to observe that evening may still be below the horizon.
I don't know how ZWO might address that, however if I do properly understand your request, I have a simple solution I use to deal with the problem you mention that you at least could try immediately.
I simply use my Planisphere. Essentially I just adjust my Planisphere to show both the time, as well as the span of time the particular RA and Dec coordinates for the object I wish to image both enter as well as transits my FOV. Based on that information I set my start time that PLAN. In my case I typically have about a three hour window .
I typically try to find a series of objects ( 2 or 3 ) and the times that they will rotate through that FOV one after another during the evening and set up my PLAN accordingly.
Not to hijack your request, but I would add for ZWO's consideration, that in addition to your request, they also add the ability to set Two different PLAN start times in a single PLAN. That would be very helpful for the times when a second object of interest may not pass through the FOV for several hours after the first.
