I get that some deliveries can reach the warehouses at different times and that is not a problem if we talk about 2-3 weeks difference. But if THE SAME warehouse (seems to be Australia) always get the stuff 2-3 months later than the other something has to change in order to enhance customer satisfaction.
This can be done in two or three ways. 1) Close the outlier warehouse and have the people there order from other warehouses (Fedex or DHL from EU to Australis is 2-4 days which will better for the consumers than waiting 2-3 extra months, even if the price will be higher). Or 2) use a second printer close to that warehouse. Many big book publishers uses different printers to secure their release dates. Or 3) use option 1) but keep the warehouse. Clients near that warehouse can buy the books with more expensive shipping for the first months but will get cheaper postage if they wait.