If you're driving you'd have enough time to go back to your WDW hotel and freshen up.
Were you planning to go straight from the themepark? If so what time does the themepark close that day? You need to allow 30 minutes from the park if you're using Disney transport. If you need to "eat up a little time" I would suggest a little shopping at the Rainforest Cafe at AK (they have some excellent bargains there at times). AKL itself is a great place to spend a little time, there are three animal "lookout" areas to watch the Zebra , Ostrich etc and it's a good way to check out the pool etc if you want to help with a future choice to stay at this hotel.
You need to check into the podium by 7:15 , but you can always check in a little earlier.
It does depend on how you like to spend your day, if it's EVERYTHING AT 100 mph then maybe you could bring your reservation time forward, but if you want to allow yourself a more relaxed experience ( IMHO the best way to enjoy AK) I would try to take my time at AK to enjoy all it has to offer.
Working backwards from a 7:30 meal I would
check into the podium by 7:10-7:15
get to the hotel about 6:00-6:15 ( they have a nice bar for the adults and Disney movies in the lobby for the kids as well as the animal look outs and an interesting gift shop) IMHO you could easily spend 90 minutes just checking out the hotel
Leave AK themepark about 5:30 (If the park closes at 5:00 spend 30 minutes checking out Rainforest gift shop)
At AK park itself, if you take in all the shows ( including birds of prey show) ,take time over the walk through bird gardens (and IMHO you need to sit and take 5 minutes to adjust to the atmosphere and pace of these. So many people just march through them, without taking in the beautiful free flying birds. To start seeing and hearing the birds it takes a few minutes to "tune in" your senses), visit the "Conservation station" , take time over the wonderful tree of life carvings and make sure you really enjoy the park. You can also take time for a few drink breaks at the bar area in Africa.
At AK, Disney (known for it's attention to detail) has excelled itself in that aspect, it's done SO well that you need to take your time a little more than in other parks to see that aspect of it. So if you can afford the time ( and it appears you can) don't try to take the park at 1,000 miles an hour and see everything that is hidden from immediate view.
