Windows Server OEM P2V

Hi - I am about to undertake around 30 P2V's of Windows Server 2003 SP2 OEM licensed servers.

Its been a while since I did some P2V's but do remember around 4 years ago I had to call Microsoft during one.

I have got Server 2012 licensing to cover the VM's but was looking for some information on what I can do before the P2V to get round the need to call Microsoft? Also it will help me with the downtime and migration time planning for the P2V's

Thanks

JB