Google has already rolled out 5.0.1 for the Nexus 6 and earlier today we announced that the Nexus 7 is already receiving the rollout of 5.0.2. Certainly Google will have this build ready to go for the Nexus 6 soon however you don't have to wait for them to begin rolling it out if you are bootloader unlocked with a custom recovery installed. Dhacker29, most well known for his extensive development for Motorola devices, has already released his build of 5.0.2 AOSP and GAPPS for the Nexus 6. According to Dhacker all the normal stuff should be working. As this is an unofficial build there may be a bug or two. Head to the link below for the download.
5.0.2 Rom
LP Gapps