Timing of invoicing and cashflow with fixed (but also potentially variable) length of jobs and periods b/w jobs

[matthewlmcdonald]

I'm looking for a formula(s) to forecast both invoice and cashflow timing under the following circumstances:

1. Commencement of forecast period = Day 1
2. Average job length = 50 days
3. Average period between jobs = 12 days
4. Average job value = $150K
5. There is an average GP% of 30% on each job, the supplier invoices for which are received and paid within 7 days from commencement of the job;
6. Job is invoiced 50% at commencement (i.e. Day 1), with final 50% invoiced at job completion (i.e. Day 50);
7. First invoice is paid on average 12 days after issue, while the second invoice is paid on average 50 days after it being issued;
8. I want to have the capacity to alter one or more variables, such that overall timing of invoicing and cashflow "re-calibrates" according to the changes I make to the variables;
9. While I'd like t track he exact days for each job, I'm preparing a monthly P&L and cashflow budget, so the timing each invoice and cash receipt us fall within a month;
10. The main variation in variables is likely be the start, as I have actual values and timing of jobs within current pipeline. However, beyond this, I'll be reliant on average forecast variables, per above
11. I'd like to be able to forecast monthly P&L and cashflows based on above.

Any assistance would be appreciated. I apologise in advance if I've structured this post incorrectly.

Thanks in advance.
Mat