I wonder if Fisker have any parts that got delayed / canceled due to the Japan quake-and-tsunami...
Anyway, I would be cautious about doing a linear projection here:
If it takes until the end of August to get to 750 cars or even 1000 considering dealer demos etc. and production began on March 21st, that equates to around 200 a month.
(200 per month is a linear projection: April, May, June, July, August = 5 months, 1000 / 5 = 200.) Fisker have said repeatedly that they will start slow and ramp up. If they have made 1000 by early August, it could, for instance, be: 5 in April, 25 in May, 125 in June, 625 in July, etc. This is an exponential growth series where each month they produce five times as many as the previous month.
Now, I'm not suggesting that $n = 5 \sup \mbox{month}$ (to write it in LaTeX-ese) is the actual ramp-up equation either. It's much more likely that they make 1 per day initially, then 3, then suddenly jump to 12, then 15, for instance. Basically, work out kinks, then when it looks good, increase the pressure and find lots of new kinks, work those out, etc.
All of this will make it hard for Fisker, even with all the information, to predict when anyone's car would actually arrive. So I sympathize with them. Still, they really do owe a lot more visibility to those who have orders in....