Some of the items are not going to be serial controlled at go-live or for some time after post go-live.
At some point post go-live if the client decides to have it under serial control, what are the pros & cons or how difficult is the switch ?
It is something which we can achieve w/o turning it into a big side project ?
You won't be able to update the serial number attribute while you got stock on hand.
You need to issue out the stock and then update the serial number attribute.
Whether you need to do it as a project depends upon the number of items and stock on hand.
Highlevel steps are:
1. Issue out the stock
2. Update the item attribute
3. Re-receive the stock with appropriate serial numbers.