Can I set up 2012 R2 server as a DC but install 2008 AD on it?

I was told I cannot upgrade from Win 2003 domain directly to 2012 R2.

in-place upgrade, no
a 2012 R2 domain controller can co-exist with a 2003 domain controller as long as the domain/forest functional level is 2003

if I can set up the AD server with 2012 R2 first, and then upgrade the AD level to 2008

you can install a 2012 R2 server in a 2003 domain
you can't raise the functional level to anything higher than your lowest windows version; in this case is 2003

Thanks Seth.
Currently we have two Win 2003 DC servers. To upgrade to AD 2012, my idea is:
1. Add two more DC servers in Win 2012. So we have total four DC: two 2003 and two 2012. At this point, all four DC are in AD 2003 level.
2. Have them sync at least one day.
3. Demote the two 2013 DCs.
4. Raise AD level from 2003 to 2012.

Will the above work? Please advise if I miss anything?

Before adding DCs - and AFTER adding DCs - I strongly recommend checking the health of AD by running DCDIAG /C /E /V and resolving any unexplained errors.