The first group I got were thick, including starters, and all my replacements direct from Wotc were thick. This made me believe thick’s were first. Can’t be 100% certain though.
Edit: one more thing. My test sheet is thick also.
We know it’s first. The WOTC manager said they increased the pressure, which caused the thin stamp and the rest of the stamps from Jungle onward to be thin.
Why wouldn’t you want to discuss the old WOTC manager? Did he do something to hurt the hobby? Another question that I’m sure has been answered at some point… with all the people who worked at wotc why hasn’t anyone come forward with printing numbers. Surely someone, somewhere, knows something.