That's probably good timing. The lodge is less than a 5-minute ride from AK but then factoring in possible bus waiting times, loading and unloading times, and walking to the restaurant, you should be just fine.
we have done this a couple of times. we watch the 4:00 parade at AK then head to the bus stop. since this park usually closes at 5:00 and everyone rushes out around then we have found the busses to be plentiful. 5:30 is a good time for a PS at boma too, it starts to get very busy after 6:00. enjoy
katypop