I could be wrong, but I think everything gets posted on 1 January, and not sooner. It would really be nice to get the fabric quantities to start collecting now... I participated in the 2012 BOM and nothing was available until the first month. Can't speak for previous BOMs because I did not participate. The only thing I could imagine doing now is browsing through some quilt books to see what comes
close to this design and see what the fabric requirements there are. I think the overall size of the quilt was posted so you you might be able to get an approximation that way. Just a thought... but be prepared to improvise if your approximation is short.