How to set up recurring orders for office supplies on Amazon?

How do I actually set up a fixed, reliable recurring order schedule for office supplies on Amazon Business because the standard Subscribe and Save stuff is driving me crazy with the shifting delivery windows? I have been managing the procurement and front office stuff for a small law firm here in downtown Austin for about six years now so I usually know my way around a dashboard but this has me totally stumped. I have a monthly budget of around 500 dollars to keep us stocked on legal pads, those specific Pilot G2 pens the partners are obsessed with, and heavy-duty toner for our old laser printer.

I know the basics of Subscribe and Save but the problem is that the system keeps messing with my dates. It will decide that because I didnt use enough toner one month (according to its weird algorithm) it should push the next delivery back two weeks but then we run out and I am scrambling. Plus it splits my orders into like five different shipments which makes my monthly accounting and invoice matching a total nightmare for the quarterly audit. I need everything to arrive on the 1st of the month, every single month, no exceptions.

I tried looking through the Amazon Business Prime settings to see if there is a more 'pro' version of recurring orders that functions like a traditional vendor contract where I just set a quantity and a date and it sticks to it regardless of what the 'smart' shipping logic thinks. I even tried making a dedicated list but that still requires me to go in and manually checkout every time which defeats the whole purpose of automation. Is there a specific toggle in the business settings for 'Recurring Deliveries' that is separate from the consumer-facing Subscribe and Save? I feel like I am missing something super obvious here but the UI is so cluttered with ads and suggestions lately that I cant find the actual procurement tools I need. If anyone has a workaround or knows where that specific setting is hiding it would save me a lot of stress before the partners start complaining about the empty supply closet again...