In general, the anime studio release their cels 
after the series completed its airing.  Some do 
release early when the show is still airing, it 
depends.  And some cels are stolen from the anime 
studio, like Pokemon, the studio never released 
them officially to the public.
Also, the anime studio sometimes has to get 
approvals first, like investors, sponsors or 
distributors or even TV channels.  If they're fine 
with it, they will let them go to the public 
early.  If not, they will release them very late 
or even not to release them forever, like the case 
for Evangelion.

About Daa! Daa! Daa!, it's created by JC Staff, I 
believe they still use cels, not computers yet.  I 
don't know when they will release the cel, pray 
them to release soon.