[Samba] Best way to move from windows 2000 server AD to Samba4

[sr]

Hello,
I'm trying to move to one Samba4 AD from a windows 2000 server, and I'm 
currently trying this:
- adding a win 2003 server to active directory
- adding a samba4 server to active directory thanks to the windows 2003 
server.
- moving roles to samba4
- switch off windows 2000 and 2003
Is it the best way to do?
Do I try to transfer or seize the 5 roles?
Do I need to do an additional task after switching off the old servers ?
thanks for helping! :)
Samuel