Olaf,
Yes I understand, but in our company it is ok to deliver early.
Understood. As it happens, in my company, for our customers, it is not OK to deliver earlier than the customer's requested date. That being said, every company is different.
Thank you, I have not found any ATP feature allowing to do this.
I would say that your search was diligent, and I am not surprised at your findings. I don't believe SAP offers this feature in standard ATP configuration. Confirmation at first date is typically the goal during ATP, earlier confirmations are generally not supported in standard.
In some companies, deliveries are created manually, using manually created dates, when they wish to deliver orders earlier than first date. Caveat Emptor. This can result in shortages for other orders against the same material/plant.
I suggest that if you need to actually confirm the sales doc itself earlier than first date, you use enhancements to override standard SAP behavior. Speak to your developers.
Best Regards & Good Luck,
DB49