Take Zelda right, up, left, and drop her in front of the slab. Now go back right and down the steps for fairies (all-you-can-catch!) and a Piece of Heart!
Now you will have to wait until Zelda calls you telepathically at 18:48 so fly back to the overworld and finish anything you didn't do before.
Now would also be a good time to dig for that last Piece of Heart.
Go meet the Mole; he's on the left side of the Archers' Bridge (18:34). He tunnels out in the bottom-right of the Death Mountain summit.
When Zelda calls you, fly up to the mountain (that triangle thing is a selectable ducky destination). After the animation you get the Silver Arrows; thus armed with the Master Sword and the Silver Arrows, go bravely through the teleporter.
Ram the rock-pile to the left of Ganon's fortress to find a Great Fairy.
Go out and up to the very far right of the fortress and what's that? Yes... yet another Piece of Heart. Ganon left it out especially for you I guess. Now slash the evil, evil magic bat thing and go into the fortress.