I am not sure where you are seeing that the park closes at 7 that night. At the time of this writing the November times for shows and park times are not yet published on the website, though they should be within a month. You should be able to see these in time before you have to make your reservations.
I expect you will find that by November the park will still be open later than 7 on a Friday. Since sunset is around 6:40pm at that time of year in Orlando, certainly it is unlikely that fireworks could be any earlier than 7pm.
If it were me I would make a dinner reservation for 7pm. That way the fireworks will either go on during your dinner (AWESOME!), or not so long after you are done. In the latter case you can go down to the beach to watch (AWESOME, in a different way).
FYI, if I were to guess I bet the fireworks will be at 8. That is when the were that Friday last year.