Loading SP2 On Our Win2K servers

Next week we’re going to load SP2 on our Windows 2000 servers. We have two active directory servers, an exchange server, conference server, connector server and OWA server. Is there a proper order to loading the service pack? We’re thinking we need to start at the top, the first AD server since it’s the Global Catalogue and work our way down. Or is it okay to load it on a couple of the member servers first to test out how it reacts in our environment?