Seems that GDR2 OS + Amber Firmware update will start rolling out from July for all other Lumia WP8 devices than Lumia 925. Australian carrier Telstra’s latest software update table puts a date of 8th July for approval of the GDR2 update for Lumia 920 and 15th July for Lumia 520. They were still waiting for submission of the update by Nokia at the time of publishing of this table.
Anyways if past trends are the way to go, then other regions may get the update one or two weeks before Telstra. So, may be next week or 1st of week of July may bring some news on the GDR2 and Amber update.
In case you want to know what these two updates bring, here are some of the articles of interest,