Hi Chokoholic,
Do you Carb count? If so it would be best to await each course and inject just prior to each one with the insulin required for that course only. (Don't do it in the toilets though, too much bacteria)
If you are on fixed doses, the best time would be just before the main course, though with a meal like that it would be very difficult for you to keep your BGs in check.
When I was on MDI I used to inject just prior to each part of a meal, but always kept some fast acting carbs just in case. Now on an insulin pump I can do it even easier.
(I have a work meal on the 19th so know how nervous you will be feeling, it'll be the first time since I got my pump.)