I have put this list together from my past and previous experience and exposure as Project Lead and Manager. Many of these may or may not be applicable depending Project type, Rollout or upgrade, Implemetation. But ideally these points mentioned below are usually missed and or not under consideration until the situation arises. But project management practise says that one should always be prepared for the worst even before it shows up at the door step. I have seen on several occasions when we as a team had to go back and review the strategy to mitigate the risk of missing the timeline
Project plan should include the below activities
1 Check for prerequisite version of 11i needed for R12 upgrade
2 DB upgrade for supporting/as needed to 10g or 11g
3 Server capacity ( RAM, HDD) increase as needed to support 10g or 11g accordingly
4 Necessary pre-requisite patches to be applied for R12 as given for the corresponding version and research on the new patches released for that version and modules related.
5 Data Conversion/Migration planning
6 Instance planning and availability plan
7 Requirement gathering
8 Requirement signoff
9 Module Related Patches Verification
10 Cut Over Activities
11 Seeded Functional Setup steps.
12 Custom components functional design documents
13 Data Conversion/Migration Functional Design
14 Customization Technical design documents
15 Data Conversion/Migration Technical Design
16 Code Build
17 Unit Testing
18 System Integration Testing
19 User acceptance testing
20 Regression Testing
21 Volume Testing
22 Pre Production activities
23 Cut Over Activities
To top it all these should have bookmarks in the Risk Management document. Ideally each step can be flagged off red depending on the stage or the current status of the project affairs.