Can I make up the batter ahead and wait till dinner is over to bake?

It probably would not be a good idea, because the recipe also contains baking soda as an additional leavener. That will start reacting as soon as liquids and dry ingredients combine. However, you could mix up to the point where you add in the dry ingredients, and keep those separate until you finish eating. Then desert could be ready by the time you get the cleanup sorted out, and some digestion has provided room to really enjoy it!