A colleague and I work for a large retailer checking that all of the promotional income has been billed and collected. (In this circumstance, promotional income is money received from our suppliers for promoting their products in store.
We are in the process of designing a new system for our team and are increasingly arguing about which direction the system should take.
The process for agreeing and getting promotional income is:
1) Buyers agree the deal and confirm on email with the vendor
2) The deal should be entered into a promotions database
3) The promotions database is used by another team to raise invoice requests
4) The invoice requests are used by the sales ledger team to raise invoices and post the double entry
One of us wants to start our work at point 2) and work forward to 4), one of us wants to start our work at point 4) and work to point 1)
What would you do?