R12 upgrade timings

We are in the process of upgarding our EBS 11i to r12 (12.1.3, with 12.1.1 being the intermediate stage). the platform will be Redhat linux 5 on vmware. We will appreaciate if you could share the timings on the upgrades that various groups have seen on a similar environment. I would like to later add other dicussions specific to this environment. We are aware that each of thr groups will have different setups etc such as different financial modules installed. Thanks.