Answer: Sorry, Ann-Marie, but whatever you order now will ship now. You need to know when your first frost/freeze date is in the fall and then count backwards however many days the particular plant needs to mature. I would also add an extra 10 days.
So if Avenger Broccoli takes 50-60 days, I would plant it 60-70 days before that first frost date. Also add an allowance for the number of shipping days to determine the right time to order. This would be the rule of thumb for all our fall vegetable plants.
Here is a map for fall frost dates: http://www.ncdc.noaa.gov/img/climate/freezefrost/Fall28F_hires.jpg
Hope this helps. GHS