"Why didn't they fund it all?"
Because it is multi-year project. $1.2 billion in this year, more later.
" When will they start to build it?"
NOW. (billions were spent prior, btw; it is misleading to say nothing was done; check out Duncan Hunters Congressional website that goes back to his efforts since the 1990s on this!)
When's groundbreaking going to happen?
If what you say is true, then we should start to see construction beginning very soon. If what you said is accurate.