Hi All

I just ordered my 707 frame with the handlebar.
I'm planning to go for a grx rx815 DI2 2x11 groupset but as I've never installed a DI2 group before I'm wondering what specific parts to order. (Junction boxes and cables).
Do I go from a battery in the seat post to a junction box near the bottom bracket and a y-split in the handle bars?

Can't wait for painting to be done, it will take 5 weeks to paint I was told.