How to track revenue over time for a consulting engagement

We are using SuiteCRM 7.11.18.

We have a company division that performs consulting work for our customers. A typical project may last 3 months and cost $60,000. The opportunity therefore has a $60,000 value, but the tricky thing is that the actual revenue is billed in monthly portions: this might be $15,000 for month_1, $22,000 for month_2, and $23,000 for month_3. We’d like to forecast the actual revenue by month, but I can’t see way to do this easily. We don’t know in advance what the breakdown will be, but it’s estimated at the start of each time period (i.e., each month). It’s entirely possible that the initial concept of a 3 month project will change to 4 months or even longer, since customers delay things all the time.

Does anybody have a suggestion about how this might be accomplished? One way I thought of is to use the Projects module and associate the revenue with an invoicing activity. Would it be easier to just create 3 invoices that are always in draft mode and associate the expected revenue for each month with an invoice?

Following. I get this request from clients all the time.

I kind of like the simple solution @oplowman proposes, the 3 draft invoices. You can see them from the detail view in a subpanel (I suppose), maybe all that’s needed after that is a tiny bit of custom code getting a nice total, or perhaps two totals (already paid / outstanding).