I was doing some vatting of Weller 12 and Weller OWA and had read different opinions on whether you could just drink it after the blending or that you should wait to let the flavors mingle. I did a couple of blends of 60% OWA (using a 1-liter bottle) and 40% W12 (using a 750ml bottle), and had enough left of each for a 50/50 blend of them. I tried it right off the bat and thought "blech!", not good. I just tried it again two weeks later, and it was phenomenal! Not like the Pappy 15 that it's supposed to emulate, but pretty darn close. So now I'm a believer in letting the blend sit for a while.