Calculating a billing cycle time

Hi Experts,

I have been tasked with calculating the billing cycle for organisation. Basically what I want to calculate is the time it took to generate an invoice, from the proposed billing date to the actual date the invoice was generated.

So I want to figure out the time it hits the VF04 bill due list ready to bill to the actual date the invoice is created.

I am wondering is there any tables that will give me this information?

Thanks for your help and sorry I cannot be any clearer.

Thanks you,

Gary.