As seen on the main story of MacRumors there is a specific quote that jumps out:
6 weeks would put us at early July.
EDIT: I noticed twoodcc noticed the same thing as me a few min earlier.
Those people noted that the advanced training was unique, saying that "Apple never puts out product training this far ahead of a product launch. This training material is roughly 6 weeks early, they said, having arrived in the form of a single training module on Tuesday.
6 weeks would put us at early July.
EDIT: I noticed twoodcc noticed the same thing as me a few min earlier.