Since you're so early in, I'd suggest starting over. Takes me an in game week to prepare if I'm relaxing, four days if I'm being efficient.

Next time, make a shield. I'd recommend the tower shield if you're not used to the parry timing of the buckler, which you probably aren't yet. Then a flint axe will do, and two meats and a berry, or a honey if you have one. That shield is enough to block both his lightning and his antler strike with minimal damage. Then get a couple melee hits in between attacks. It takes a little while, but it will slowly wear him down.

Make sure there's nothing dangerous in the area that might join in, like if you're close to a Black Forest where the pine trees are.

Added: If you are intent on getting this to work, try going up, raise the ground, get on top of a rock, build up a tree, etc. That confuses all ground based mobs. Not sure what the range is on that lightning though.