Hi Shawn,
Thank you so much for visiting the Disney Parks Moms Panel with your question.
Disney's Beach Club Villas is such a great resort. I love the charming beach theme, and the short walking distance to Epcot is amazing!
I think that your timing will be tight, but possibly could work. I typically suggest that guests budget between one and two hours from the time that you land to the time that you are at your resort when taking advantage of Disney's Magical Express transportation. One hour assumes that your plane lands on time, you walk quickly to and check in to Disney's Magical Express, get on a motorcoach that leaves immediately, and that the motorcoach goes to your resort first. Some of the variables that could push this as high as two hours are that you might need to wait for other guests to arrive for the motorcoach that you are placed on, and that the motorcoach might stop at multiple other resorts before yours.
This would put you at Disney's Beach Club Villas between 4:25 p.m. and 5:25 p.m. If you get there close to 4:25 p.m., no problem! You would probably even have time to check into your villa and drop off some of your things that you have with you at your villa. If you get there closer to 5:25 p.m., I suggest that you ask Bell Services to hold and items that you do not want to take with you to dinner and head straight to the bus stop to catch a bus to Downtown Disney. Another option if you are running a bit on the late side is to take a taxi to Downtown Disney. This will be at an additional cost, but might be worth the time that you save.
Overall I think that your plan is possible, but if I were you I might see if you can change your dinner reservation for about 30 minutes later to give yourself a little extra time. I hope that these thoughts are helpful for you, Shawn. Please let us know if you have any further questions!