The Auction House lock is not going to be implemented. You will still be able to list auctions until the update. Please see the reply to this thread from TrionBrasse for more info.
In preparation for the Erenor Eternal (3.5) update the ability to list items on the Auction House will be temporarily disabled on all servers until 3.5 is released.
Here are the times we’ll be locking the AH in each region:
EU – 12:55 AM UTC on June 5th
NA – 7:55 AM PDT on June 5th
Items listed for auction will not be cancelled but no new items can be listed after the AH lock occurs. After 3.5 is released we’ll make it possible to list items on the AH as before. Please plan accordingly. PLEASE SEE POST BELOW!
NORTH AMERICA: Legacy Auction House clusters will be reconfigured to match the EU setup where all NA Legacy Servers are on the same cluster. Note that Fresh AH cluster(s) for NA or EU will not be modified in any way at this time.