Geeze old man, no wonder you shoot girly weight bows... your shoulder is dislocated from patting yourself on the back.
Maybe I missed where he said what kind of bow he was making or what his draw length was. If we don't know, how can we tell him how long to make it? He might want a trilam that's a 56" osage recurve, or maybe a 72" juniper English longbow... and I don't know that I'd grind any of em 1/4" thick.
Just for reference... two 1/4" osage lams in a 64" bamboo backed d/r longbow trilam can easily be a 70+# @ 28" bow.
Some of it comes down to how much wood you want to, or need to remove during tillering. I don't want to remove a bunch of wood to hit weight, so I'd rather they came off the form pretty close to the final thickness.
Bluegill, it doesn't matter which one or both lams you make thicker. That said, I try to keep my lams about the same thickness at their centers... give or take .020". And you're right to at least consider width, especially if your bows take a noticeable amount of set during tillering and shooting them in. If so, then adding only thickness to increase draw weight can make them take more set, at least partially negating the effectiveness of the weight increase, so you might want to consider adding width instead, or in conjunction with thickness. In other words, there's more than one way to get there, and without us knowing more about what you have going on there, we're just giving you a wild guess.