The most effective phase of the Equipment Procurement Process to apply DiVOM is in the Requirements Gathering phase, when the cost of change is at its lowest. Ideally you should do this before a contract is placed with the OEM - see diagram below.
In this phase, the maximum impact can be achieved for the minimum investment. If you wait until the Deployment phase, when the equipment is operational and in production, then the costs are significantly higher and can be prohibitive.
Requirements Gathering, or Equipment Specification, is the ideal phase to make changes, when the cost of change is at its lowest.
The fact that this phase occurs during the OEM's sales cycle means you can get some features ‘thrown in’ which would be extremely expensive later on in the project. Also, dealing with your OEM before placing the contract means that there is competitive pressure on them and they will make commitments here that would be much more expensive later.
Using DiVOM to measure your OSE during Equipment Procurement means you can be more certain that your technology will operate according to your requirements at the most advantageous price. The DiVOM process also gives you an industry standard method of evaluating and selecting alternative solutions.