How to upgrade SEPM 11.x to latest 12.x Version

Hello;

We are planning to upgrade the SEPM servers to 12.x version. please check the below current scenario & advice for the best practice ideas etc

-- 3 SEPM Manager running with approximate 50,000 clients ( including NAC)

-- 2 SQL server cluster for SEPM.

-- All client are getting Updates via GUP.

-- SEPM's version is  11.0.6300.803.

-- all clients ruuning on 11 version. 

Awaiting for your reply..

Thanks & Best Regards;