Just to add to thebluesbarn's post.

I suggest beginning on the accoustic for one other reason : it harder to get a good sound on the accoustic.

If you can easely do a F on the accoustic it will seem a lot easier when you start playing electric. Also goes for speed. You'll be faster on an electric than accoustic, well most of us anyway.

Build strenght and accuracy on the accoustic, it's going to make your life a lot easier afterwards.