Good advice from Donny. I think a bigger issue is doing 40 minutes of your keyboard stuff which I assume is oldie oriented and then jumping in the DJ thing for the others for 20 minutes. Its tough to go back to the mellower keyboard standards once you start the current party music. I would suggest doing the keyboard at appropriate times, like in the beginning , cocktail hour if there is one, during dinner, and a few sections in between the dance music with some slower tunes for romantic dancing. This all of course depends on the crowd and using your experience to read them.
Have a great gig.